The BIOS optimization guide v5.8

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Th e BI OS Opt im iza t ion Gu ide r e v. 5 .8

All trademarks used are properties of their respective owners. Copyright © 1998-2001 Adrian Wong. All rights reserved.

BIOS Features Setup

(Part 1)

Virus Warning / Anti-Virus Protection Options : Enabled, Disabled, ChipAway When Virus Warning is enabled, the BIOS will flash a warning message whenever there's an attempt to access the boot sector or the partition table. You should leave this feature enabled if possible. Note that this only protects the boot sector and the partition table, not the entire hard disk. However, this feature will cause problems with the installation of certain software. One good example is the installation routine of Win95/98. When enabled, this feature will cause Win95/98's installation routine to fail. Disable it before installing such software. Also, many disk diagnostic utilities that access the boot sector can trigger the error message as well. You should first disable this option before using such utilities. Finally, this feature is useless for hard disks that run on external controllers with their own BIOS. Boot sector viruses will bypass the system BIOS and write directly to such hard disks. Such controllers include SCSI controllers and UltraDMA 66 controllers. Some motherboards will have their own rule-based anti-virus code (ChipAway) incorporated into the BIOS. Enabling it will provide additional anti-virus protection for the system as it will be able to detect boot viruses before they have a chance to infect the boot sector of the hard disk. Again, this is useless if the hard disk is on a separate controller with its own BIOS.

CPU Level 1 Cache Options : Enabled, Disabled This BIOS setting can be used to enable or disable the CPU's L1 (primary) cache. Naturally, the default setting is Enabled. This feature is useful for overclockers who want to pinpoint the cause of their unsuccessful overclocking. I.e. if a CPU cannot reach 500MHz with the L1 cache enabled and vice versa; then the L1 cache is what's stopping the CPU from reaching 500MHz stably. However, disabling the L1 cache in order to increase the overclockability of the CPU is a very bad idea, especially in highly pipelined designs like Intel's P6 family of processors (Pentium Pro, Celeron, Pentium II, Pentium !!!).

CPU Level 2 Cache Options : Enabled, Disabled This BIOS setting can be used to enable or disable the CPU's L2 (secondary) cache. Naturally, the default setting is Enabled. This feature is useful for overclockers who want to pinpoint the cause of their unsuccessful overclocking. I.e. if a CPU cannot reach 500MHz with the L2 cache enabled and vice versa; then the L2 cache is what's stopping the CPU from reaching 500MHz stably. Users may choose to disable L2 cache in order to overclock higher but the trade-off isn't really worth it.

CPU L2 Cache ECC Checking Options : Enabled, Disabled This feature enables or disables the L2 cache's ECC checking function (if available). Enabling this feature is recommended because it will detect and correct single-bit errors in data stored in the L2 cache. It will also detect double-bit errors but not correct them. Still, ECC checking stabilizes the system, especially at overclocked speeds when errors are most likely to creep in. There are those who advocate disabling ECC checking because it reduces performance. The performance difference is negligible, if at all. However, the stability and reliability achieved via ECC checking is real and substantial. It may even enable you to overclock higher than is possible with ECC checking disabled. So, enable it for added stability and reliability.

Processor Number Feature Options : Enabled, Disabled This feature is only valid if you install a Pentium !!! processor. It will most probably not appear unless you have the Pentium !!! processor installed. This feature enables you to control whether the Pentium !!!'s serial number can be read by external programs. Enable this if your secure transactions require you to use such a feature. But for most people, I think you should disable this feature to safeguard your privacy.

Quick Power On Self Test Options : Enabled, Disabled When enabled, this feature will shorten some tests and skip others that are performed during the booting up process. Thus, the system boots up much quicker. Enable it for faster booting but disable it after making any change to the system to detect any errors that may slip through the Quick Power On Self Test. After a few error-free test runs, you can reenable this option for faster booting without impairing system stability.

Boot Sequence Options : A, C, SCSI/EXT C, A, SCSI/EXT C, CD-ROM, A CD-ROM, C, A D, A, SCSI/EXT (only when you have at least 2 IDE hard disks) E, A, SCSI/EXT (only when you have at least 3 IDE hard disks) F, A, SCSI (only when you have 4 IDE hard disks) SCSI/EXT, A, C SCSI/EXT, C, A A, SCSI/EXT, C LS/ZIP,C This feature enables you to set the sequence in which the BIOS will search for an operating system. To ensure the shortest booting time possible, select the hard disk that contains your operating system as the first choice. Normally, that would be drive C but if you are using a SCSI hard disk, then select SCSI. Special : Some motherboards (i.e. ABIT BE6 and BP6) have an extra onboard IDE controller. The BIOS options in these motherboards replaces the SCSI option with an EXT option. This allows the computer to boot from an IDE hard disk on the 3rd or 4th IDE ports (courtesy of the extra onboard IDE controller) or from a SCSI hard disk. If you

want to boot from an IDE hard disk running off the 1st or 2nd IDE ports, do not set the Boot Sequence to start with EXT. Note that this function has to work in conjunction with the Boot Sequence EXT Means function.

Boot Sequence EXT Means Options : IDE, SCSI This function is only valid if the Boot Sequence function above has EXT settings and this function has to cooperate with the Boot Sequence function. This function allows you to set whether the system boots from an IDE hard disk that's connected to any of the extra two IDE ports found on some motherboards (i.e. ABIT BE6 and BP6) or a SCSI hard disk. To boot from an IDE hard disk that's connected to the 3rd or 4th IDE port, courtesy of the extra onboard IDE controller), you'll first have to set the Boot Sequence (above) function to start with EXT first. For example, the EXT, C, A setting. Then, you will have to set this function, Boot Sequence EXT Means to IDE. In order to boot from a SCSI hard disk, set the Boot Sequence (above) function to start with EXT first. For example, the EXT, C, A setting. Then, you will have to set this function, Boot Sequence EXT Means to SCSI.

BIOS Features Setup

(Part 2)

First Boot Device Options : Floppy, LS/ZIP, HDD-0, SCSI, CDROM, HDD-1, HDD-2, HDD-3, LAN, Disabled This feature allows you to set the first device from which the BIOS will attempt to load the operating system (OS) from. Note that if the BIOS is able to load the OS from the device set using this feature, it naturally won't load another OS, if you have another on a different device. For example, if you set Floppy as the First Boot Device, the BIOS would boot the DOS 3.3 OS which you have placed in the floppy disk but won't bother loading Win2k even though it may be residing on your hard disk drive C. As such, this is useful for troubleshooting purposes and for installing an OS off a CD. The default setting is Floppy. But unless you boot often from the floppy drive or need to install an OS from a CD, it's better to set your hard disk (usually HDD-0) as the First Boot Device. That will shorten the booting process.

Second Boot Device Options : Floppy, LS/ZIP, HDD-0, SCSI, CDROM, HDD-1, HDD-2, HDD-3, LAN, Disabled This feature allows you to set the second device from which the BIOS will attempt to load the operating system (OS) from. Note that if the BIOS is able to load the OS from the device set as the First_Boot_Device, any setting toggled by this feature will have no effect. Only if the BIOS fails to find an OS on the First_Boot_Device, will it then attempt to find and load one on the Second Boot Device. For example, if you set Floppy as the First Boot Device but left the floppy disk out of the drive, the BIOS will then load Win2k which you have installed on your hard disk drive C (set as Second Boot Device). The default setting is HDD-0, which is first detected hard disk, usually the one attached to the Primary Master IDE channel. Unless you have a removable drive set as the First Boot Device, this feature has very little use. HDD-0 is a perfectly fine choice although you can set an different device to serve as an alternative boot drive.

Third Boot Device Options : Floppy, LS/ZIP, HDD-0, SCSI, CDROM, HDD-1, HDD-2, HDD-3, LAN, Disabled This feature allows you to set the third device from which the BIOS will attempt to load the operating system (OS) from. Note that if the BIOS is able to load the OS from the device set as the First_Boot_Device or the Second_Boot_Device, any setting toggled by this feature will have no effect. Only if the BIOS fails to find an OS on the First_Boot_Device and Second_Boot_Device, will it then attempt to find and load one on the Third Boot Device. For example, if you set Floppy as the First Boot Device and the LS-120 drive as the Second Boot Device but left both drives empty, the BIOS will then load Win2k which you have installed on your hard disk drive C (set as Third Boot Device). The default setting is LS/ZIP. Unless you have a removable drives set as the First and Second Boot Devices, this feature has very little use. LS/ZIP is a perfectly fine choice although you can set an different device to serve as an alternative boot drive.

Boot Other Device Options : Enabled, Disabled This feature determines whether the BIOS will attempt to load an OS from the Second or Third Boot Device if it fails to load one from the First_Boot_Device. The default is Enabled and it's recommended that you leave it as such. Otherwise, if the BIOS cannot find an OS in the First Boot Device, it will then halt the booting process with the error message "No Operating System Found" even though there's an OS on the Second or Third Boot Device.

Swap Floppy Drive Options : Enabled, Disabled This feature is useful if you want to swap the logical arrangement of the floppy drives. Instead of opening up the casing to do it physically, you can just set this feature to Enabled. Then, the first drive will be mapped as drive B: and the second drive, mapped as drive A:; which is the opposite of the usual convention. This feature is also useful if both the floppy drives in your system are of different formats and you want to boot from the second drive. That's because the BIOS will only boot from floppy drive A:.

Boot Up Floppy Seek Options : Enabled, Disabled This feature controls whether the BIOS checks for a floppy drive while booting up. If it cannot detect one (either due to improper configuration or physical inavailability), it will flash an error message. It will also detect if the floppy drive has 40 or 80 tracks but since all floppy drives in use today have 80 tracks, this check is redundant. This feature should be set as Disabled for a faster booting process.

Boot Up NumLock Status Options : On, Off This feature controls the functionality of the Numeric Keyboard at boot up. If set to On, the Numeric Keyboard will function in the numeric mode (for typing out numbers) but if set to Off, it will function in the cursor control mode (for controlling the cursor). The setting of this feature is entirely up to your preference.

BI OS Feat ures Set up

(Part 3)

Ga t e A2 0 Opt ion Opt ion s : Norm al, Fast This feat ure det erm ines how Gat e A20 is used t o addr ess m em ory abov e 1MB. When t his opt ion is set t o Fa st , t he m ot herboard chipset cont rols t he operat ion of Gat e A20. But when set t o N or m a l, a pin in t he keyboard cont roller cont rols Gat e A20. Set t ing Gat e A20 t o Fast im proves m em ory access speed and t hus, ov erall syst em speed, especially wit h OS/ 2 and Windows. This is because OS/ 2 and Windows ent er and leave prot ect ed m ode via t he BI OS a lot so Gat e A20 needs t o swit ch oft en fr om enabled t o disabled and back again. Set t ing t his feat ure t o Fa st im proves m em ory access perform ance abov e 1MB because t he chipset is m uch fast er in swit ching Gat e A20 t han t he k eyboard cont roller. I t is recom m ended t hat y ou set it t o Fa st for fast er m em or y accesses.

I D E H D D Block M ode Opt ion s : Enabled, Disabled The I DE HDD Block Mode feat ure speeds up hard disk access by t ransferring dat a from m ult iple sect or s at once inst ead of using t he old single sect or t ransfer m ode. When y ou enable it , t he BI OS will aut om at ically det ect if your hard disk support s block t ransfers and configure t he proper block t ransfer set t ings for it . Up t o 6 4 KB of dat a can be t ransferred per int errupt wit h I DE HDD Block Mode enabled. Since virt ually all hard disks now support block t ransfer s, t here is norm ally no reason w hy I DE HDD Block Mode should not be enabled. How ev er, if you are running WinNT, bew are. According t o Chris Bope, Windows NT does not support I DE HDD Block Mode and enabling I DE HDD Block Mode can cause corrupt ed dat a. Ryu Connor confirm ed t his by sending m e a link t o a Micr osoft art icle about Enhanced I DE operat ion under WinNT 4.0. According t o t his art icle, I DE HDD Block Mode ( and 32- bit Disk Access) had been observ ed t o cause dat a corrupt ion in som e cases. Microsoft r ecom m ends t hat WinNT 4.0 user s disa ble I DE HDD Block Mode. On t he ot her hand, Lord Mike ask ed som eone in t he know and he was t old t hat t he dat a corrupt ion issue w as t ak en v er y seriously at Microsoft and t hat it had been corr ect ed t hrough Serv ice Pack 2. Alt hough he couldn't get an official st at em ent from Microsoft , it 's probably safe enough t o enable I DE HDD Block Mode if you ar e running WinNT, j ust as long as you upgrade t o Service Pack 2. I f y ou disable I DE HDD Block Mode, only 5 1 2 byt e s of dat a can t ransferr ed per int errupt . Needless t o say, t hat degrades perform ance quit e a bit . So, only disable I DE HDD Block Mode if you are running WinNT. Ot her t han t hat , you should enable it for opt im al perform ance.

For m ore det ailed infor m at ion on I DE HDD Block Mode, check out our Speed Dem onz' guide on I DE Block Mode!

3 2 - bit D isk Acce ss Opt ion s : Enabled, Disabled 32- bit Disk Access is a m isnom er because it doesn't r eally allow 32- bit access t o t he hard disk. What it act ually does is set t he I DE cont roller t o com bine t w o 16- bit reads from t he hard disk int o a single 32- bit double word t ransfer t o t he processor. This m akes m or e efficient use of t he PCI bus as fewer t ransact ions ar e needed for t he t ransfer of a part icular am ount of dat a. How ev er, according t o a Microsoft art icle about Enhanced I DE operat ion under WinNT 4.0, 32- bit disk access can cause dat a corrupt ion under WinNT in som e cases. Microsoft recom m ends t hat WinNT 4.0 users disable 32- bit Disk Access. On t he ot her hand, Lord Mike ask ed som eone in t he know and he was t old t hat t he dat a corrupt ion issue w as t ak en v er y seriously at Microsoft and t hat it had been corr ect ed t hrough Serv ice Pack 2. Alt hough he couldn't get an official st at em ent from Microsoft , it 's probably safe enough t o enable I DE HDD Block Mode if you ar e running WinNT, j ust as long as you upgrade t o Service Pack 2. I f disabled, dat a t ransfers fr om t he I DE cont roller t o t he processor w ill t hen occur only in 16- bit s. This degrades perfor m ance, of course, so y ou should enable it if possible. Disable it only if you face t he possibilit y of dat a corrupt ion. You can also find m ore inform at ion on t he WinNT issue abov e in our Speed Dem onz' guide on I DE Block Mode!

Type m a t ic Ra t e Se t t in g Opt ion s : Enabled, Disabled This feat ure enables you t o cont rol t he k ey st r oke repeat rat e when you depr ess a key cont inuously. When enabled, you can m anually adj ust t he set t ings using t he t w o t ypem at ic cont rols ( Typem at ic Rat e and Typem at ic Rat e Delay) . I f disabled, t he BI OS will use t he default set t ing.

Type m a t ic Ra t e ( Ch a r s/ Se c) Opt ion s : 6, 8, 10, 12, 15, 20, 24, 30 This is t he rat e at which t he k eyboard will repeat t he k eyst roke if you pr ess it cont inuously. This set t ing will only work if Typem at ic Rat e Set t ing is Enabled.

Type m a t ic Ra t e D e la y ( M se c) Opt ion s : 250, 500, 750, 1000 This is t he delay, in m illiseconds, before t he key board aut om at ically repeat s t he keyst rok e t hat you have pressed cont inuously. This set t ing will only w ork if Typem at ic Rat e Set t ing is Enabled.

Se cu r it y Se t u p Opt ion s : Sy st em , Set up This opt ion will only wor k once you hav e cr eat ed a password t hr ough PASSW ORD SETTI N G out in t he m ain BI OS scr een. Set t ing t his opt ion t o Syst e m will set t he BI OS t o ask for t he passw ord each t im e t he sy st em boot s up. I f y ou choose Se t u p , t hen t he passw ord is only required for access int o t he BI OS set up m enus. This opt ion is useful for sy st em adm inist rat ors or com put er r esellers who j ust want t o k eep novice users fr om m essing around wit h t he BI OS. :)

BI OS Feat ures Set up

(Part 4)

PCI / V GA Pa le t t e Snoop Opt ion s : Enabled, Disabled This opt ion is only useful if you use an MPEG car d or an add- on card t hat m akes use of t he graphics card's Feat ure Connect or. I t cor rect s incor r ect color r eproduct ion by " snooping" int o t he graphics card's fram e buffer m em ory and m odifying ( synchronizing) t he inform at ion delivered from t he graphics card's Feat ure Connect or t o t he MPEG or add- on card. I t will also solve t he pr oblem of display inversion t o a black scr een aft er using t he MPEG card.

Assign I RQ For V GA Opt ion s : Enabled, Disabled Many high- end graphics accelerat or cards now require an I RQ t o funct ion properly. Disabling t his feat ure wit h such cards will cause im proper oper at ion and/ or poor perform ance. Thus, it 's best t o m ake sure you enable t his feat ure if you are having problem s wit h your graphics accelerat or card. How ev er, som e low - end cards don't need an I RQ t o run norm ally. Check your graphics card's docum ent at ion ( m anual) . I f it st at es t hat t he card does not require an I RQ, t hen you can disable t his feat ure t o release an I RQ for ot her uses. When in doubt , it 's best t o leav e it enabled unless you really need t he I RQ.

M PS V e r sion Cont r ol For OS Opt ion s : 1.1, 1.4 This opt ion is only valid for m ult iprocessor m ot herboards as it specifies t he version of t he Mult iprocessor Specificat ion ( MPS) t hat t he m ot herboard will use. The MPS is a specificat ion by which PC m anufact urers design and build I nt el archit ect ure syst em s wit h t wo or m ore pr ocessors. MPS v er sion 1.4 added ext ended configurat ion t ables t o im prov e support for m ult iple PCI bus configurat ions and im prove fut ure expandabilit y. I t is also required for a secondary PCI bus t o w ork wit hout t he need for a bridge. New er v ersions of server operat ing syst em s will generally support MPS 1.4 and as such, y ou should change t he BI OS Set up from t he default of 1.1 t o 1.4 if your operat ing syst em support s version 1.4. Leave it as 1.1 only if you are running older server OSes. Eugene Tan inform ed m e t hat t he set t ing for WinNT should be 1.4.

OS Se le ct For D RAM > 6 4 M B Opt ion s : OS/ 2, Non- OS/ 2 When t he sy st em m em ory is m or e t han 64MB in size, OS/ 2 differs from ot her operat ing syst em s ( OS) in t he w ay it m anages t he RAM. So, for sy st em s running I BM's OS/ 2 operat ing syst em , select OS/ 2 and for sy st em s running ot her operat ing syst em s, select N on- OS/ 2 .

H D D S.M .A.R.T. Ca pa bilit y Opt ion s : Enabled, Disabled This opt ion enables/ disables support for t he hard disk's S.M.A.R.T. capabilit y. The S.M.A.R.T. ( Self Monit oring Analysis And Report ing) t echnology is support ed by all curr ent hard disks and it allows t he early predict ion and warning of im pending hard disk disast ers. You should enable it so t hat S.M.A.R.T. awar e ut ilit ies can m onit or t he hard disk's condit ion. Enabling it also allow s t he m onit oring of t he hard disk's condit ion over a net w or k. Ther e's no perform ance advant age in disabling it even if you don't int end t o use t he S.M.A.R.T. t echnology. How ev er, t her e's a possibilit y t hat enabling S.M.A.R.T. m ay cause spont aneous reboot s in net wor ked com put ers. Johnat han P. Dinan m ent ioned such an experience wit h S.M.A.R.T. enabled. S.M.A.R.T. m ay be sending packet s of dat a t hrough t he net work ev en t hough t her e's not hing m onit oring t hose dat a packet s. This m ay have caused t he spont aneous reboot s t hat he had experienced ( Com m ent # 103) . So, t ry disabling H D D S.M .A.R.T. Ca pa bilit y if you ex perience r eboot s or crashes w hile you are on a net w ork .

Re por t N o FD D For W in 9 5 Opt ion s : Enabled, Disabled I f y ou are using Windows 95/ 98 wit hout a floppy disk drive, select En a ble d t o release I RQ6. This is required t o pass Windows 95/ 98's SCT t est . You should also disable t he Onboard FDC Cont roller in t he I nt e gr a t e d Pe r iph e r a ls scr een when t here's no floppy drive in t he sy st em . I f you set t his feat ure t o D isa ble d, t he BI OS will not report t he m issing floppy drive t o Win95/ 98.

D e la y I D E I n it ia l ( Se c) Opt ion s : 0, 1, 2, 3, ..., 15 The boot ing process of new BI OSes is m uch fast er t hese day s. Thus, som e I DE devices m ay not be able t o spin up fast enough for t he BI OS t o det ect t hem during t he boot ing up process. This set t ing is used t o delay t he init ializat ion of such I DE devices during t he boot ing up process.

Leav e it at 0 if possible for fast er syst em boot ing. But if one or m or e of your I DE devices fail t o init ialize while boot ing, increase t he value of t his set t ing unt il t hey all init ialize properly.

BI OS Feat ures Set up

(Part 5)

Vide o BI OS Sha dow in g Opt ion s : Enabled, Disabled When t his feat ur e is enabled, t he Video BI OS is copied t o t he syst em RAM for quicker access. Shadowing im prov es t he BI OS' per form ance because t he BI OS can now be read by t he CPU t hrough t he 64- bit DRAM bus as opposed t o t he 8- bit XT bus. This seem s quit e at t ract ive since t hat 's at least a 100x increase in t ransfer r at e and t he only price is t he loss of som e syst em RAM which is used t o m irr or t he ROM cont ent s. How ev er, m odern operat ing syst em s bypass t he BI OS com plet ely and access t he graphics card's hardwar e direct ly. So, no BI OS calls are m ade and no benefit fr om BI OS shadowing is realized. I n light of t his, t here's no use in wast ing RAM j ust t o shadow t he Video BI OS when it 's not used at all. Ryu Connor confirm ed t his by sending m e a link t o a Microsoft art icle about Shadowing BI OS under WinNT 4.0. According t o t his art icle, shadowing t he BI OS ( irrespect ive of what BI OS it is) does not bring about any perform ance enhancem ent s because it 's not used by WinNT. I t w ill only w ast e m em ory. Alt hough t he art icle did not say anyt hing about Win9x, it 's t he sam e for Win9x as it 's based on t he sam e Win32 archit ect ure. Not only t hat , som e m anuals also allude t o t he possibilit y of sy st em inst abilit y when cert ain gam es access t he RAM region t hat has already been used t o shadow t he Video BI OS. How ev er , t his is no longer an issue as t he shadowed RAM r egion has been m ov ed far fr om t he reach of pr ogram s. What could be an issue is if only 32KB of t he video BI OS is shadow ed. New er video BI OSes are larger t han 32KB in size but if only 32KB is shadowed and t he r est is left in t heir original locat ions, t hen st abilit y issues m ay arise when t he BI OS is accessed. So, if y ou int end t o shadow t he video BI OS, you'll need t o ensure t hat t he ent ire video BI OS is shadow ed. I n m any cases, only t he C000- C7FF region is shadowed by default . To corr ect t hat , you'll need t o : •

enable video BI OS shadowing ( for t he C000- C7FF region) a nd

•

enable t he shadowing of t he rem aining port ions, i.e. C800- CBFF, unt il t he ent ire video BI OS is shadowed.

That t ip was generously cont ribut ed by X. Finally, m ost graphics cards now com e wit h Flash ROM ( EEPROM) which is m uch fast er t han t he old ROM and ev en fast er t han DRAM. Thus, t her e's no longer a need for video BI OS shadowing and t here m ay ev en be a perform ance advant age in not shadowing! I n addit ion, you shouldn't shadow t he video BI OS if y our gr aphics card com es wit h a Flash ROM because you wouldn't be able t o updat e it s cont ent s if shadowing is enabled. On t he ot her hand, t here m ay st ill be a use for t his feat ure. Som e DOS gam es st ill m ake use of t he video BI OS because t hey don't direct ly access t he graphics processor ( alt hough m ore graphical ones do) . So, if y ou play lot s of old DOS gam es,

you can t ry enabling Video BI OS Shadowing for bet t er perform ance. This t ip is court esy of I van Warr en. For an ex cellent overview of video BI OSes and t heir shadowing, check out William Pat rick McNam ara's explanat ion : The w hole issu e is hist or ica l in n a t ur e . W a y ba ck w he n ha vin g a V GA v ide o ca r d w a s a big t h ing, gr a phics ca r ds w e r e pr e t t y du m b a n d f a ir ly sim ple a s w e ll. The y a m ou n t e d t o a ch u n k of m e m or y t h a t r e pr e se n t e d t h e pix e ls on t he scr e e n . To cha nge a pix e l, you cha nge d t he m e m or y r e pr e se n t in g it . Things lik e ch a n ging color pa le t t e s, scr e e n r e solut ions, e t c w e r e don e by w r it in g t o a se t of r e gist e r s on t he vide o ca r d. H ow e v e r , e v e r yt hing w a s done by t he pr oce ssor . Since int e r fa cin g w it h ha r dw a r e va r ie s w it h t h e ha r dw a r e , t a lk in g t o t he v ide o ca r d de pe nde d on t he ca r d y ou h a d inst a lle d. To he lp solve t he pr oble m , t h e v ide o ca r d inclu de d a BI OS chip on it . Qu it e sim ply t he vide o BI OS w a s a n e x t e n sion t o t h e syst e m BI OS. I t w a s sim ply a docum e nt e d se t of fu n ct ion ca lls a pr ogr a m m e r cou ld u se t o int e r f a ce w it h t h e v ide o ch ipse t . So w hy did BI OS sh a dow ing com e a bout ? Th e m e m or y u se d t o st or e t h e BI OS on a vide o ca r d is usua lly som e sor t of EPROM ( Ele ct r ica lly Pr ogr a m m a ble Re a d Only M e m or y) . A ve r y fa st EPROM h a s a n a cce ss t im e of 1 3 0 - 1 5 0 ns, w hich is a bout t h e sa m e a s t he m e m or y in a n 8 0 8 6 ba se d com pu t e r . Also, t h e bus w idt h is 8 bit s. As com pu t e r s got f a st e r ( x 3 8 6 , x 4 8 6 , e t c) a nd ga m e s got m or e gr a ph ica l, ca llin g t he BI OS got t o be m or e of a bot t le ne ck . To h e lp a lle via t e t h e pr oble m , t he v ide o BI OS w a s m ove d t o t h e fa st e r 1 6 bit syst e m m e m or y t o spe e d t h ings up. Act u a lly m ost gr a ph ica l D OS ga m e s r a r e ly ca ll t h e BI OS a n y w a y . M ost int e r a ct w it h t h e ch ipse t dir e ct ly if possible . A quick sum m a r y : I n t he " old da ys" , vide o BI OS didn't r e a lly ha ve m uch t o do w it h r unn in g t h e v ide o ca r d. I t sim ply pr ovide d a se t of f unct ion ca lls t o m a k e a de ve lope r s lif e e a sie r . " An d n ow for som e t h in g com ple t e ly diffe r e n t ....." N e w v ide o ca r ds, one s t h a t ha ve a cce le r a t e d f unct ion s, f a ll int o a diffe r e nt ca t e gor y. The y a ct u a lly ha v e a pr oce ssor built on t h e ca r d. I n t h e sa m e w a y t ha t t he sy st e m BI OS t e lls you pr oce ssor h ow t o st a r t your com put e r , your vide o BI OS t e lls you vide o pr oce ssor how t o displa y im a ge s. Th e r e a son, ne w ca r d h a ve fla sh ROM s on t h e m , is so t ha t t he m a nuf a ct u r e r s ca n fix a n y bu gs t h a t e x ist in t h e code . Any ope r a t ing syst e m t h a t u se s t h e a cce le r a t e d fe a t ur e s of a v ide o ca r d, com m u nica t e s dir e ct ly w it h t he pr oce ssor on t he ca r d, giving it a se t of com m a nds. This is t h e j ob of t he vide o dr ive r . The ide a is, t he dr iv e r pr e se nt s t h e ope r a t ing syst e m w it h a docum e nt se t of funct ion ca lls. W he n on of t h e se ca lls is m a de , t h e dr iv e r se nds t he a ppr opr ia t e com m a n d t o t he vide o pr oce ssor . The vide o pr oce ssor t h e ca r r ie s out t he com m a nds a s it pr ogr a m m ing ( vide o BI OS) dict a t e s. As fa r a s sha dow in g t he v ide o BI OS goe s, it doe sn't m a t t e r . W in dow s, Linux , or a ny ot h e r OS t ha t u se s t h e a cce le r a t e d fu n ct ion s n e ve r dir e ct ly com m u n ica t e s w it h t he v ide o BI OS. Good 'ole D OS h ow e ve r st ill doe s, a n d t he sa m e f unct ion s t h a t e x ist e d in t he or igina l VGA ca r ds e x ist in t he ne w 3 D ca r ds. D e pe nding on h ow t he v ide o int e r fa ce on D OS pr ogr a m s is w r it t e n, t he y m a y be ne fit fr om ha vin g t he vide o BI OS sh a dow e d. Quick Sum m a r y # 2 : I n t oda y's a cce le r a t e d vide o ca r ds, t h e m a in j ob of t he vide o BI OS is t o pr ovide a pr ogr a m f or t he vide o pr oce ssor ( RI V A TN T2 , Voodoo3 , e t c) t o r u n so t h a t it ca n do it s j ob. I nt e r fa ce be t w e e n t h e v ide o ca r d a nd soft w a r e is done t hr ough a com m a nd se t pr ov ide d by t he dr ive r

a nd r e a lly h a s not hin g t o do w it h t he vide o BI OS. The or igina l BI OS funct ion a r e st ill a v a ila ble t o m a int a in ba ck w a r ds VGA com pa t ibilit y. Mor e on t his can be found from his e- m ail ( Com m ent # 91) . Check it out for m ore inform at ion. For a final confirm at ion on w hy you should not shadow t he video BI OS, check out St eve Hauser's account of his bad experience wit h video BI OS shadowing : A f e w ye a r s ba ck ( pr oba bly '9 6 or so) I h a d a M a t r ox M ille niu m ca r d a nd t he BI OS I h a d a t t he t im e de fa ult e d t o sha dow in g e n a ble d for t he VGA BI OS... * W ELL* t he M ille n iu m h a d a la r ge r t h a n 3 2 KB BI OS. So, w he n I r a n a BI OS fla sh, t he f ir st bit j u st copie d int o t h e sh a dow in sy st e m RAM , w hile t he r e st hit t he vide o ca r d it se lf. N e e dle ss t o sa y, w it h t he fir st 3 2 KB block m issin g, t he BI OS of t he ca r d w a s com ple t e ly cor r upt e d a nd no lon ge r f unct ione d. Alr e a dy you ca n se e how sha dow in g * CAN * ge t you in r e a l t r ou ble w it h ca r e le ssly w r it t e n f la sh soft w a r e ( t h a t d oe sn't che ck for it f ir st ) . N ow , I ca n't a t t e st t o a ny spe e d incr e a se s/ de cr e a se s it m a y h a ve ca use d but h e r e 's t h e r e a lly pe r t ine nt pa r t , w h a t h a ppe n e d w it h t he ca r d a ft e r it n o longe r h a d a BI OS.... I t st ill w or k e d! ( m ost ly) ... ALL 'D OS' v ide o m ode s w e r e gone - t ot a l bla nk scr e e n. But you ca n h e a r t h e com put e r be e p a nd t he n boot nor m a lly. Once t he W indow s GUI ( w it h pr ope r dr ive r s) loa de d, it ope r a t e d 1 0 0 % nor m a lly. All v ide o a cce le r a t ion m ode s w or k e d fine ... * EX CEPT* a nyt hing r e la t e d t o D OS ( e ve n a D OS w in dow w it h in W in dow s it se lf) w a s 1 0 0 % de v oid of t e x t . This inclu de s t h e 'bu ilt - in' VGA ( 6 4 0 x 4 8 0 x 1 6 colour s) sa fe m ode w hich a lso didn't w or k a t a ll ( sin ce it doe sn't use dr iv e r s) . So, a ppa r e nt ly y ou a r e 1 0 0 % cor r e ct in a ssum ing t h a t m ode r n vide o ca r ds do n ot u se t he 'D OS a ddr e ssa ble ' BI OS for a nyt hin g e x ce pt dr ive r le ss VGA/ EGA/ t e x t m ode s... N ow , t ha t 's not t o sa y 'BI OS upda t e s' a r e use le ss, a s t h e a ct ua l BI OS of t h e ca r d inclu de s fa r m or e t h a n t h e lit t le t a ble D OS ca n se e . I t ca n inclu de m icr o- code w it h pa t ch e s for pr oble m s ( j u st lik e h ow m ot h e r boa r d BI OS u pda t e s ca n f ix ce r t a in pr oce ssor pr oble m s) . I 've give n you a t le a st one ca se now w he r e e na bling BI OS sh a dow ing ca n ca u se SERI OUS a n d pe r m a ne nt h a r m t o t h e vide o ca r d it se lf... Aft e r t he fa ile d 'sh a dow e d' f la sh, t h e ca r d w a s ne ve r a ga in a ble t o r e n de r D OS vide o m ode s or t e x t ; a nd fu r t he r BI OS upda t e s w ould not w or k since t he y 'f a ile d t o de t e ct cu r r e n t BI OS r e vision'. Sha dow ing Addr e ss Ra nge s ( x x x x x - x x x x x Sha dow ) Opt ion s : Enabled, Disabled This opt ion allows y ou t o decide if t he m em ory block of an addon card in t he address range of xxx xx- xx xxx w ill be shadowed or not . Leav e it as disabled if you don't hav e an addon card using t hat m em ory range. Also, like Video BI OS Shadowing, t her e's no benefit in enabling t his opt ion if you run Win95/ 98 and have t he pr oper drivers for your addon card. Ryu Connor confirm ed t his by sending m e a link t o a Microsoft art icle about Shadowing BI OS under WinNT 4.0. According t o t his art icle, shadowing t he BI OS ( irrespect ive of what BI OS it is) does not bring about any perform ance enhancem ent s because it 's not used by WinNT. I t w ill only w ast e m em ory. Alt hough t he art icle did not say anyt hing about Win9x, it 's t he sam e for Win9x as it 's based on t he sam e Win32 archit ect ure. I n addit ion, I van War ren warns t hat if you ar e using an add- on card w hich is using som e CXXX- EFFF area for I / O, t hen shadowing would probably prevent t he card from working because t he m em ory R/ W request s m ight not be passed t o t he I SA bus.

Chipset Feat ures Set up

(Part 1)

SD RAM CAS La t e n cy Tim e Opt ion s : 2, 3 This cont rols t he t im e delay ( in clock cycles - CLKs) t hat passes before t he SDRAM st art s t o car ry out a read com m and aft er receiving it . This also det erm ines t he num ber of CLKs for t he com plet ion of t he first part of a burst t r ansfer . Thus, t he low er t he lat ency, t he fast er t he t ransact ion. How ever, som e SDRAM cannot handle t he lower lat ency and m ay becom e unst able and lose dat a. So, set t he SDRAM CAS Lat ency Tim e t o 2 for opt im al perfor m ance if possible but increase it t o 3 if your syst em becom es unst able.

SD RAM Cycle Tim e Tr a s/ Tr c Opt ion s : 5/ 6, 6/ 8 This feat ure t oggles t he m inim um num ber of clock cy cles required for t he Tras and t he Tr c of t he SDRAM. Tr a s r efer s t o t he SDRAM's Row Act iv e Tim e , which is t he lengt h of t im e in which t he row is open for dat a t ransfer s. I t is also known as M inim um RAS Pulse W idt h . Tr c, on t he ot her hand, refers t o t he SDRAM's Row Cycle Tim e , which det erm ines t he lengt h of t im e for t he ent ire r ow- open, row- refr esh cycle t o com plet e. The default set t ing is 6 / 8 which is m or e st able and slower t han 5 / 6 . How ev er, 5 / 6 cycles t he SDRAM fast er but m ay not leav e t he row open long enough for dat a t ransact ions t o com plet e. This is especially t rue at SDRAM clockspeeds abov e 100MHz. Therefore, y ou can t ry 5 / 6 for bet t er SDRAM perform ance but should increase it t o 6 / 8 if your syst em becom es unst able.

SD RAM RAS- t o- CAS D e la y Opt ion s : 2, 3 This opt ion allows y ou t o insert a delay bet w een t he RAS ( Row Addr e ss St r obe ) and CAS ( Colum n Addr e ss St r obe ) signals. This occurs when t he SDRAM is writ t en t o, read fr om or refr eshed. Nat urally, reducing t he delay im prov es t he perform ance of t he SDRAM while increasing it reduces perfor m ance. So, reduce t he delay from t he default value of 3 t o 2 for bet t er SDRAM perform ance. How ev er, if y ou ar e facing syst em st abilit y issues aft er reducing t he delay, reset t he value back t o 3 .

SD RAM RAS Pr e ch a r ge Tim e Opt ion s : 2, 3 This opt ion set s t he num ber of cy cles required for t he RAS t o accum ulat e it s charge before t he SDRAM refr eshes. Reducing t he precharge t im e t o 2 im prov es SDRAM perform ance but if t he precharge t im e of 2 is insufficient for t he inst alled SDRAM, t he SDRAM m ay not be refr eshed properly and it m ay fail t o ret ain dat a. So, for bet t er SDRAM perform ance, set t he SD RAM RAS Pr e ch a r ge Tim e t o 2 but increase it t o 3 if you face sy st em st abilit y issues aft er r educing t he precharge t im e.

SD RAM Cycle Le n gt h Opt ion s : 2, 3 This feat ure is sim ilar t o SDRAM CAS Lat ency Tim e. I t cont r ols t he t im e delay ( in clock cycles - CLKs) t hat passes befor e t he SDRAM st art s t o car ry out a read com m and aft er receiving it . This also det erm ines t he num ber of CLKs for t he com plet ion of t he first part of a burst t r ansfer . Thus, t he lower t he cy cle lengt h, t he fast er t he t ransact ion. However, som e SDRAM cannot handle t he low er cycle lengt h and m ay becom e unst able. So, set t he SDRAM Cycle Lengt h t o 2 for opt im al perform ance if possible but increase it t o 3 if your syst em becom es unst able.

SD RAM Le a doff Com m a nd Opt ion s : 3, 4 This opt ion allows y ou t o adj ust t he leadoff t im e needed before t he dat a st ored in t he SDRAM can be accessed. I n m ost cases, it is t he access t im e for t he first dat a elem ent in a burst . For opt im al perform ance, set t he value t o 3 for fast er SDRAM access t im es but increase it t o 4 if you are facing syst em st abilit y issues.

SD RAM Ba n k I nt e r le a ve Opt ion s : 2- Bank, 4- Bank, Disabled This feat ure enables you t o set t he int erleav e m ode of t he SDRAM int erface. I nt erleaving allows banks of SDRAM t o alt ernat e t heir refr esh and access cycles. One bank will undergo it s r efresh cy cle while anot her is being accessed. This im proves perform ance of t he SDRAM by m asking t he refr esh t im e of each bank . A closer exam inat ion of int erleav ing will reveal t hat since t he r efr esh cycles of all t he SDRAM banks are st aggered, t his produces a kind of pipelining effect . I f t her e ar e 4 bank s in t he sy st em , t he CPU can ideally send one dat a r equest t o each of t he SDRAM banks in consecut ive clock cycles. This m eans in t he first clock cycle, t he CPU will send an address t o Bank 0 and t hen send t he next address t o

Bank 1 in t he second clock cy cle before sending t he t hird and fourt h addresses t o Banks 2 and 3 in t he t hird and fourt h clock cycles respect ively. The sequence would be som et hing like t his : 1. CPU sends address # 0 t o Bank 0 2. CPU sends address # 1 t o Bank 1 and r eceives dat a # 0 from Bank 0 3. CPU sends address # 2 t o Bank 2 and r eceives dat a # 1 from Bank 1 4. CPU sends address # 3 t o Bank 3 and r eceives dat a # 2 from Bank 2 5. CPU r eceives dat a # 3 fr om Bank 3 As a result , t he dat a fr om all four request s will arrive consecut ively from t he SDRAM wit hout any delay in bet ween. But if int erleaving was not enabled, t he sam e 4address t ransact ion would be roughly like t his : 1. SDRAM refreshes 2. CPU sends address # 0 t o SDRAM 3. CPU r eceives dat a # 0 fr om SDRAM 4. SDRAM refreshes 5. CPU sends address # 1 t o SDRAM 6. CPU r eceives dat a # 1 fr om SDRAM 7. SDRAM refreshes 8. CPU sends address # 2 t o SDRAM 9. CPU r eceives dat a # 2 fr om SDRAM 10. SDRAM refreshes 11. CPU sends address # 3 t o SDRAM 12. CPU r eceives dat a # 3 fr om SDRAM As y ou can see, wit h int erleaving, t he first bank st art s t ransferring dat a t o t he CPU in t he sam e cycle t hat t he second bank receives an address fr om t he CPU. Wit hout int erleaving, t he CPU w ould send t he address t o t he SDRAM, receive t he dat a request ed and t hen w ait for t he SDRAM t o refr esh before init iat ing t he second dat a t ransact ion. That wast es a lot of clock cy cles. That 's why t he SDRAM's bandwidt h increases wit h int erleaving enabled. How ev er, bank int erleaving only wor ks if t he addresses request ed consecut ively ar e not in t he sam e bank . I f t hey are, t hen t he dat a t ransact ions behave as if t he banks were not int erleaved. The CPU will have t o wait t ill t he first dat a t ransact ion clears and t hat SDRAM bank refreshes before it can send anot her address t o t hat bank. Each SDRAM DI MM consist s of eit her 2 banks or 4 banks. 2- bank SDRAM DI MMs use 16Mbit SDRAM chips and are usually 32MB or less in size. 4- bank SDRAM DI MMs, on t he ot her hand, usually use 64Mbit SDRAM chips t hough t he SDRAM densit y m ay be up t o 256Mbit per chip. All SDRAM DI MMs of at least 64MB in size or gr eat er are 4banked in nat ure.

I f you are using a single 2- bank SDRAM DI MM, set t his feat ure t o 2- Bank. But if you are using t w o 2- bank SDRAM DI MMs, you can use t he 4- Bank opt ion as w ell. Wit h 4bank SDRAM DI MMs, you can use eit her int erleave opt ions. Nat urally, 4- bank int erleav e is bet t er t han 2- bank int erleave so if possible, set it t o 4- Bank. Use 2- Bank only if you are using a single 2- bank SDRAM DI MM. Not e, howev er, t hat Award ( now part of Phoenix Technologies) recom m ends t hat SDRAM bank int erleaving be disabled if 16Mbit SDRAM DI MMs are used.

Chipset Feat ures Set up

(Part 2)

SD RAM Pr e ch a r ge Con t r ol Opt ion s : Enabled, Disabled This feat ure det erm ines whet her t he pr ocessor or t he SDRAM it self cont rols t he precharging of t he SDRAM. I f t his opt ion is disa ble d, all CPU cy cles t o t he SDRAM will result in an All Banks Precharge Com m and on t he SDRAM int erface, which im proves st abilit y but reduces perform ance. I f t his feat ur e is enabled, pr echarging is left t o t he SDRAM it self. This r educes t he num ber of t im es t he SDRAM is precharged since m ult iple CPU cycles t o t he SDRAM can occur before t he SDRAM needs t o be refreshed. So, enable it for opt im al perform ance unless y ou ar e facing syst em st abilit y issues wit h t his opt ion enabled.

D RAM D a t a I n t e gr it y M ode Opt ion s : ECC, Non- ECC This BI OS set t ing is used t o configure y our RAM's dat a int egrit y m ode. ECC st ands for Er r or Ch e ck in g a n d Cor r e ct ion and it should only be used if you are using special 72- bit ECC RAM. This will enable t he syst em t o det ect and corr ect single- bit er rors. I t w ill also det ect double- bit errors t hough it will not correct t hem . This provides increased dat a int egrit y and syst em st abilit y at t he expense of a lit t le speed. I f you own ECC RAM, enable it ( set ECC) t o benefit from t he incr eased dat a int egrit y. Aft er all, you hav e already spent so m uch for t he expensive ECC RAM so why not use it ? ;) I f you are not using ECC RAM, choose N on- ECC inst ead.

Re a d- Ar ou nd- W r it e Opt ion s : Enabled, Disabled This BI OS feat ur e allows t he processor t o ex ecut e r ead com m ands out of order, as if t hey are independent fr om t he writ e com m ands. So, if a read com m and point s t o a m em ory address whose lat est writ e ( cont ent ) is in t he cache ( wait ing t o be copied int o m em ory) , t he read com m and will be sat isfied by t he cache cont ent s inst ead. This negat es t he need for t he read com m and t o go all t he way t o t he DRAM and im proves t he efficiency of t he m em ory subsyst em . Ther efor e, it is recom m ended t hat you enable t his feat ure.

Syst e m BI OS Ca che a ble Opt ion s : Enabled, Disabled This feat ure is only valid when t he sy st em BI OS is shadowed. I t enables or disables t he caching of t he sy st em BI OS ROM at F0 0 0 0 h- FFFFFh via t he L2 cache. This great ly speeds up accesses t o t he syst em BI OS. However, t his does n ot t ranslat e int o bet t er syst em per form ance because t he OS does not need t o access t he syst em BI OS m uch. As such, it would be a w ast e of L2 cache bandwidt h t o cache t he sy st em BI OS inst ead of dat a t hat are m ore crit ical t o t he sy st em 's perform ance. I n addit ion, if any program w rit es int o t his m em or y ar ea, it will result in a syst em crash. So, it is recom m ended t hat you disa ble Syst em BI OS Cacheable for opt im al syst em perform ance.

Vide o BI OS Ca ch e a ble Opt ion s : Enabled, Disabled This feat ure is only valid when t he video BI OS is shadowed. I t enables or disables t he caching of t he video BI OS ROM at C0 0 0 0 h - C7 FFFh via t he L2 cache. This great ly speeds up accesses t o t he video BI OS. How ev er, t his does n ot t ranslat e int o bet t er syst em perform ance because t he OS bypasses t he BI OS using t he graphics driver t o access t he video card's hardware direct ly. As such, it would be a w ast e of L2 cache bandwidt h t o cache t he video BI OS inst ead of dat a t hat are m or e cr it ical t o t he sy st em 's perform ance. I n addit ion, if any program w rit es int o t his m em or y ar ea, it will result in a syst em crash. So, it is recom m ended t hat you disa ble Video BI OS Cacheable for opt im al syst em perform ance.

Vid e o RAM Ca ch e a b le Opt ion s : Enabled, Disabled This feat ure enables or disables t he caching of t he video RAM at A0 0 0 0 h- AFFFFh via t he L2 cache. This is supposed t o speed up accesses t o t he video RAM. How ev er , t his does n ot t ranslat e int o bet t er syst em perform ance. Many graphics cards now have a RAM bandw idt h of 5 .3 GB/ s ( 128bit x 166MHz DDR) and t hat num ber is clim bing const ant ly. Meanwhile, SDRAM's bandwidt h is st ill st uck around 0 .8 GB/ s ( 64bit x 100MHz) or at m ost 1 .0 6 GB/ s ( 64bit x 133MHz) if you are using a PC133 syst em . Now, alt hough a Pent ium ! ! ! 650 m ay hav e a L2 cache bandwidt h of about 20.8GB/ s ( 256bit x 650MHz) , it m akes m ore sense t o cache t he really slow syst em SDRAM inst ead of t he graphics card's RAM. Also not e t hat caching t he video RAM doesn't m ake m uch sense even w it h t he Pent ium ! ! ! 's high L2 cache bandwidt h. This is because t he video RAM com m unicat es

wit h t he L2 cache via t he AGP bus which has a m axim um bandwidt h of only 1 .0 6 GB/ s using t he AGP4X prot ocol. Act ually, t hat bandwidt h is halved in t he case of t he L2 cache caching t he graphics card's RAM because dat a has t o pass in t wo direct ions. I n addit ion, if any progr am writ es int o t his m em or y ar ea, it will result in a syst em crash. So, t here's very lit t le benefit in caching t he video card's RAM. I t would be m uch bet t er t o use t he processor 's L2 cache t o cache t he syst em SDRAM inst ead. I t is recom m ended t hat y ou disa ble Video RAM Cacheable for opt im al syst em perform ance. For m ore det ailed inform at ion, check out t he Video RAM Caching guide.

M e m or y H ole At 1 5 M - 1 6 M Opt ion s : Enabled, Disabled Som e special I SA cards require t his ar ea of m em or y for t hem t o w or k properly. Enabling t his funct ion reserv es t he m em ory ar ea for t he card's use. I t will also prev ent t he sy st em fr om accessing m em or y abov e 16MB. This m eans t hat if you enable t his funct ion, your OS can only use up t o 15MB of RAM, irrespect ive of how m uch RAM your sy st em act ually has. So, always disable t his funct ion unless y our I SA card absolut ely requires t his m em ory area t o w or k properly.

Chipset Feat ures Set up

(Part 3)

8 - bit I / O Re cove r y Tim e Opt ion s : NA, 8, 1, 2, 3, 4, 5, 6, 7 The PCI bus is m uch fast er t han t he I SA bus. So, for I SA cards t o w or k properly wit h I / O cycles fr om t he PCI bus, t he I / O bus recov ery m echanism adds addit ional bus clock cycles bet w een each consecut ive PCI - originat ed I / O cycles t o t he I SA bus. By default , t he bus recovery m echanism adds a m inim um of 3.5 clock cycles bet w een each consecut ive 8- bit I / O cycle t o t he I SA bus. The opt ions above enable you t o add e v e n m or e clock cycles bet w een each consecut ive 8- bit I / O cycle t o t he I SA bus. Choosing NA set s t he num ber of delay cycles at t he m inim um 3.5 clock cycles. So, set t he 8- bit I / O Recov ery Tim e at N A if possible for opt im al I SA bus perform ance. I ncr ease t he I / O Recov ery Tim e only if you ar e having pr oblem s wit h your 8- bit I SA cards. Not e t hat t his funct ion has no m eaning if you are n ot using any I SA cards.

1 6 - bit I / O Re cove r y Tim e Opt ion s : NA, 4, 1, 2, 3 The PCI bus is m uch fast er t han t he I SA bus. So, for I SA cards t o w ork properly wit h I / O cycles fr om t he PCI bus, t he I / O bus recov ery m echanism adds addit ional bus clock cycles bet w een each consecut ive PCI - originat ed I / O cycles t o t he I SA bus. By default , t he bus recovery m echanism adds a m inim um of 3.5 clock cycles bet ween each consecut ive 16- bit I / O cycle t o t he I SA bus. The opt ions abov e enable you t o add e v e n m or e clock cycles bet w een each consecut ive 16- bit I / O cycle t o t he I SA bus. Choosing NA set s t he num ber of delay cycles at t he m inim um 3.5 clock cycles. So, set t he 16- bit I / O Recov ery Tim e at N A if possible for opt im al I SA bus perform ance. I ncr ease t he I / O Recov ery Tim e only if you ar e having pr oblem s wit h your 16- bit I SA cards. Not e t hat t his funct ion has no m eaning if you are n ot using any I SA cards.

Pa ssiv e Re le a se Opt ion s : Enabled, Disabled I f Passive Release is enabled, CPU- t o- PCI bus accesses are allowed during passive release of t he PCI bus. Ther efor e, t he processor can access t he PCI bus while t he I SA bus is being accessed. Ot her wise, t he arbit er only accept s anot her PCI m ast er access t o local DRAM. I n ot her words, only anot her PCI bus m ast er can access t he PCI bus, not t he pr ocessor. This funct ion is used t o m eet t he lat ency of t he I SA bus m ast er , which is m uch longer t han t hat of t he PCI bus m ast er. Ena ble Passive Release for opt im al perform ance. Disable it only if you are facing problem s wit h your I SA cards.

D e la ye d Tr a n sa ct ion Opt ion s : Enabled, Disabled This feat ure is used t o m eet t he lat ency of PCI cycles t o and fr om t he I SA bus. The I SA bus is m uch, m uch slower t han t he PCI bus. Thus, PCI cycles t o and fr om t he I SA bus t ak e a longer t im e t o com plet e and t his slows t he PCI bus dow n. How ev er, enabling D e la ye d Tr a nsa ct ion enables t he chipset 's em bedded 32- bit post ed writ e buffer t o support delayed t ransact ion cy cles. This m eans t hat t ransact ions t o and fr om t he I SA bus are buffered and t he PCI bus can be fr eed t o perform ot her t ransact ions w hile t he I SA t ransact ion is underw ay. This opt ion should be e na ble d for bet t er perform ance and t o m eet PCI 2.1 specificat ions. Disable it only if your PCI cards cannot work properly or if y ou ar e using an I SA card t hat is not PCI 2.1 com pliant .

PCI 2 .1 Com plia nce Opt ion s : Enabled, Disabled This is t he sam e t hing as D e la ye d Tr a nsa ct ion above. This feat ure is used t o m eet t he lat ency of PCI cycles t o and fr om t he I SA bus. The I SA bus is m uch, m uch slower t han t he PCI bus. Thus, PCI cycles t o and fr om t he I SA bus t ak e a longer t im e t o com plet e and t his slows t he PCI bus dow n. How ev er, enabling D e la ye d Tr a nsa ct ion enables t he chipset 's em bedded 32- bit post ed writ e buffer t o support delayed t ransact ion cy cles. This m eans t hat t ransact ions t o and fr om t he I SA bus are buffered and t he PCI bus can be fr eed t o perform ot her t ransact ions w hile t he I SA t ransact ion is underw ay. This opt ion should be e na ble d for bet t er perform ance and t o m eet PCI 2.1 specificat ions. Disable it only if your PCI cards cannot work properly or if y ou ar e using an I SA card t hat is not PCI 2.1 com pliant .

AGP Ape r t ur e Siz e ( M B) Opt ion s : 4, 8, 16, 32, 64, 128, 256 This opt ion select s t he size of t he AGP apert ure. The apert ure is a port ion of t he PCI m em ory address range dedicat ed as graphics m em ory address space. Host cycles t hat hit t he apert ur e range ar e forwarded t o t he AGP wit hout need for t ranslat ion. This size also det erm ines t he m axim um am ount of sy st em RAM t hat can be allocat ed t o t he graphics card for t ext ur e st orage. AGP Apert ure size is set by t he form ula : m a x im u m u sa ble AGP m e m or y siz e x 2 plu s 1 2 M B. That m eans t hat usable AGP m em ory size is less t han half of t he AGP apert ure size. That 's because t he syst em needs AGP m em ory ( uncached) plus an equal am ount of w rit e com bined m em ory area and an addit ional 12MB for virt ual addressing. This is address space, not phy sical m em ory used. The physical m em ory is allocat ed and released as needed only when Direct 3D m ak es a " cr eat e non- local surface" call. Win95 ( wit h VGARTD.VXD) and Win98 use a " wat er fall effect " . Surfaces ar e cr eat ed first in local m em or y. When t hat m em ory is full, surface creat ion spills over int o AGP m em ory and t hen syst em m em ory. So, m em ory usage is aut om at ically opt im ized for each applicat ion. AGP and syst em m em ory are not used unless absolut ely necessary . The size of t he apert ure does n ot corr espond t o per form ance so incr easing it t o gargant uan proport ions will not im prov e perfor m ance. Many graphics card, however, will require a larger t han 8MB AGP apert ur e size t o work pr operly so y ou will need t o set a m inim um of 16MB for t he AGP apert ur e size. Ev en t hen, you should set t he apert ure size at a higher set t ing so t hat it will be large enough t o accom m odat e any t ext ure st orage requirem ent s t hat y our gam es/ applicat ions m ay have. At t he m om ent , t he rule of t he t hum b is an AGP apert ure size of about 64MB t o 128MB. I ncreasing t he AGP apert ure size bey ond 128MB wouldn't really hurt perform ance but it would st ill be best t o k eep t he apert ure size t o about 64MB128MB so t hat t he GART t able won't be t oo large. As t he am ount of onboard RAM increases and t ext ur e com pr ession becom es com m onplace, t here's less of a need for t he AGP apert ure size t o increase bey ond 64MB. So, it 's recom m ended t hat you set t he AGP Apert ure Size as 6 4 M B or at m ost , 1 2 8 M B.

Chipset Feat ures Set up

(Part 4)

AGP 2 X M ode Opt ion s : Enabled, Disabled This BI OS feat ure enables or disables t he AGP2X t ransfer prot ocol. The st andard AGP1X only m akes use of t he rising edge of t he AGP signal for dat a t ransfer. At 66MHz, t his t ranslat es int o a bandwidt h of 264MB/ s. Enabling AGP 2 X M ode doubles t hat bandwidt h by t ransferring dat a on bot h t he rising and falling edges of t he signal. Therefore, w hile t he clock speed of t he AGP bus st ill rem ains as 66MHz, t he effect ive bandwidt h of t he bus is doubled. This is t he sam e m et hod by which Ult raDMA 33 derives it s perform ance boost . How ev er, bot h t he m ot herboard chipset and t he graphics card m ust support AGP2X t ransfer s befor e y ou can use t he AGP2X t ransfer pr ot ocol. I f y our graphics card support AGP2X t ransfer s, e na ble AGP 2X Mode for a higher AGP t ransfer rat e. Disable it only if you ar e facing st abilit y issues ( especially wit h Super Sock et 7 m ot herboards) or if y ou int end t o ov er clock t he AGP bus bey ond 75MHz and can't j ust disable sidebanding.

AGP M a st e r 1 W S Re a d Opt ion s : Enabled, Disabled By default , t he AGP busm ast ering device wait s for at least 2 wait st at es or AGP clock cycles befor e it st art s a read t ransact ion. This BI OS opt ion allows you t o r educe t he delay t o only 1 wait st at e or clock cycle. For bet t er AGP r ead perform ance, e n a ble t his opt ion but disable it if you experience weird graphical anom alies like wirefram e effect s and pixel art ifact s aft er enabling t his opt ion.

AGP M a st e r 1 W S W r it e Opt ion s : Enabled, Disabled By default , t he AGP busm ast ering device wait s for at least 2 wait st at es or AGP clock cycles befor e it st art s a writ e t ransact ion. This BI OS opt ion allows you t o r educe t he delay t o only 1 wait st at e or clock cycle. For bet t er AGP writ e perform ance, e n a ble t his opt ion but disable it if you experience weird graphical anom alies like wirefram e effect s and pixel art ifact s aft er enabling t his opt ion.

USW C W r it e Post ing Opt ion s : Enabled, Disabled USWC or Unca ch e a ble Spe cula t iv e W r it e Com bin a t ion im proves perform ance for Pent ium Pro syst em s ( and possibly ot her P6 pr ocessors as well) wit h graphic cards t hat have a linear fram ebuffer ( all new ones do) . By com bining sm aller dat a writ es int o 64- bit writ es, it reduces t he num ber of t ransact ions required for a part icular am ount of dat a t o be t r ansferred int o t he linear fram ebuffer of t he graphics card. How ev er, it m ay cause issues like graphic cor rupt ion, crashes, boot ing problem s, et c... if t he graphics car d does not support such a feat ure. I n addit ion, t est s using Fast Vid ( in t he old art icle - The Phoenix Pr oj ect ) have shown t hat such a set t ing can possibly de cr e a se perform ance, inst ead of increasing it ! This was observ ed wit h t he I nt el 440BX- based m ot herboard. So, if y ou are using a Pent ium Pro processor or a m ot herboard based on older chipset s, enable it for fast er graphics perform ance. I f you own a new er m ot herboard, you can t ry enabling it but m ake sure you run som e t est s t o det erm ine if t his feat ure really im prov es per form ance or not . I t 's quit e possible t hat it m ay not anyt hing at all or ev en decrease perfor m ance.

Spr e a d Spe ct r u m Opt ion s : Enabled, Disabled, 0.25% , 0.5% , Sm art Clock When t he m ot herboard's clock generat or pulses, t he ext rem e v alues ( spikes) of t he pulses cr eat es EMI ( Elect rom agnet ic I nt erfer ence) . The Spe a d Spe ct r u m funct ion reduces t he EMI generat ed by m odulat ing t he pulses so t hat t he spikes of t he pulses are reduced t o flat t er curv es. I t does so by varying t he fr equency so t hat it doesn't use any part icular frequency for m or e t han a m om ent . This reduces int er ference problem s wit h ot her elect ronics in t he ar ea. How ev er, while enabling Spread Spect rum decr eases EMI , syst em st abilit y and perform ance m ay be slight ly com prom ised. This m ay be especially t rue wit h t im ingcrit ical devices like clock- sensit ive SCSI devices. Som e BI OSes offer a Sm art Clock opt ion. I nst ead of m odulat ing t he frequency of t he pulses ov er t im e, Sm art Clock t urns off t he AGP, PCI and SDRAM clock signals when not in use. Thus, EMI can be reduced wit hout com prom ising syst em st abilit y. As a bonus, using Sm art Clock can also help reduce pow er consum pt ion. I f y ou do not hav e any EMI problem , leave t he set t ing at D isa ble d for opt im al syst em st abilit y and perfor m ance. But if you ar e plagued by EMI , use t he Sm a r t Clock set t ing if possible and set t le for En a ble d or one of t he t w o ot her values if Sm art Clock is not available. The per cent age values denot e t he am ount of j it t er ( variat ion) t hat t he BI OS per form s on t he clock fr equency. So, a lower value ( 0.25% ) is com parat ively bet t er for syst em st abilit y while a higher value ( 0.5% ) is bet t er for EMI reduct ion.

Aut o D e t e ct D I M M / PCI Clk Opt ion s : Enabled, Disabled This funct ion is sim ilar t o t he Sm a r t Clock opt ion of t he Spread Spect rum funct ion. The BI OS m onit ors t he AGP, PCI and SDRAM's act ivit y. I f t here are no cards in t hose slot s, t he BI OS t urns off t he appr opriat e AGP, PCI or SDRAM clock signals. And when t here's no act ivit y in occupied AGP / PCI / SDRAM slot s, t he BI OS t urns off t hose clock signals as well. This way, EMI ( Elect rom agnet ic I nt erfer ence) can be reduced wit hout com prom ising syst em st abilit y. This also allows t he com put er t o r educe power consum pt ion because only com ponent s t hat are running w ill use pow er. St ill, if you do not have any EMI pr oblem , leave t he set t ing at D isa ble d for opt im al syst em st abilit y and perfor m ance. Enable it only if you ar e plagued by EMI or if you want t o save m ore pow er .

Chipset Feat ures Set up

(Part 5)

Fla sh BI OS Pr ot e ct ion Opt ion s : Enabled, Disabled This funct ion prot ect s t he BI OS from accident al corrupt ion by unaut horized users or com put er viruses. When enabled, t he BI OS' dat a cannot be changed w hen at t em pt ing t o updat e t he BI OS wit h a Flash ut ilit y. To successfully updat e t he BI OS, you'll need t o disable t his Flash BI OS Prot ect ion funct ion. You should e na ble t his funct ion at all t im es. The only t im e when y ou need t o disable it is when you want t o updat e t he BI OS. Aft er updat ing t he BI OS, you should im m ediat ely re- enable it t o prot ect it against viruses.

H a r dw a r e Re se t Pr ot e ct Opt ion s : Enabled, Disabled This funct ion is useful for file servers and rout ers, et c., w hich need t o be running 24 hours a day. When enabled, t he sy st em 's hardware reset but t on will not funct ion. This prev ent s t he possibilit y of any accident al reset s. When set as D isa ble d , t he reset but t on will funct ion as norm al. I t is recom m ended t hat you leave it as D isa ble d unless you ar e running a ser ver and you hav e kids who j ust love t o press t hat lit t le red but t on running around. ;)

D RAM Re a d La t ch D e la y Opt ion s : Enabled, Disabled This is a BI OS funct ion t hat int roduces a sm all delay befor e t he sy st em reads dat a from a DRAM m odule. This feat ure was added t o facilit at e t he use of som e special SDRAM m odules t hat have unusual t im ings. You need not enable t his feat ure unless you experience st r ange syst em crashes t hat you suspect is due t o m em or y inst abilit y. So, it 's recom m ended t hat you leave it as D isa ble d unless y ou ar e experiencing som e syst em st abilit y issues. I n t hat case, y ou can e n a ble t his BI OS funct ion t o see if your DRAM m odule is one of t hose w it h unusual t im ings and t o corr ect t hat problem .

D RAM I n t e r le a ve Tim e Opt ion s : 0m s, 0.5m s This BI OS funct ion cont rols t he t im ing for r eading t he next bank of dat a when DRAM I nt erleave or SDRAM Bank I nt erleav e is enabled. Nat urally, t he lower t he t im e y ou use, t he fast er t he DRAM m odules can int erleave and consequent ly, t he bet t er t he perform ance. So, it is recom m ended t hat you set t he t im e as low as possible for bet t er DRAM perform ance. I ncr ease t he DRAM int erleav e t im e only if you face syst em st abilit y problem s.

Byt e M e r ge Opt ion s : Enabled, Disabled Byt e m erging holds 8- bit or 16- bit writ es fr om t he CPU t o t he PCI bus in a buffer wher e it is accum ulat ed and m erged int o 32- bit writ es. The chipset t hen writ es t he dat a in t he buffer t o t he PCI bus when it can. As you can see, m erging 8- bit or 16- bit w rit es reduces t he num ber of PCI t ransact ions, t hus fr eeing up bot h bandw idt h and CPU t im e. So, it 's recom m ended t hat you e na ble t his feat ure for bet t er PCI perform ance.

PCI Pipe line / PCI Pipe lining Opt ion s : Enabled, Disabled This BI OS funct ion com bines PCI or CPU pipelining wit h byt e m erging. Byt e m erging is t hen used t o enhance perform ance of t he graphics card. This funct ion cont rols t he byt e- m erge feat ure for fram ebuffer cycles. When Ena ble d , t he cont roller checks t he eight CPU Byt e Ena ble signals t o det erm ine if dat a byt es read fr om t he PCI bus by t he CPU can be m erged. So, it 's recom m ended t hat you e na ble t his feat ure for bet t er perform ance wit h your PCI graphics card. Ot her PCI devices m ay benefit from t his feat ure as w ell.

Fa st R- W Tur n Ar oun d Opt ion s : Enabled, Disabled This BI OS opt ion reduces t he delay t hat occurs when t he CPU first reads from t he RAM and t hen writ es t o it . There is norm ally an ext ra delay associat ed wit h t his swit ch from r eading t o writ ing. I f y ou enable t his opt ion, t he delay will be reduced and swit ching from read t o w rit e w ill be fast er. How ever, if your RAM m odules cannot handle t he fast er t urnaround, dat a m ay be lost and y our sy st em m ay becom e unst able. Wit h t hat in m ind, e na ble

t his opt ion for bet t er RAM perform ance unless y ou face st abilit y problem s aft er enabling it .

CPU t o PCI W r it e Buf f e r Opt ion s : Enabled, Disabled This cont rols t he CPU w rit e buffer t o t he PCI bus. I f t his buffer is disabled, t he CPU writ es direct ly t o t he PCI bus. Alt hough t his m ay seem like t he fast er and t hus, t he bet t er m et hod, t his isn't t rue. Because t he CPU bus is fast er t han t he PCI bus, any CPU w rit es t o t he PCI bus has t o wait unt il t he PCI bus is ready t o receive dat a. This prev ent s t he CPU from doing anyt hing else unt il it has com plet ed sending t he dat a t o t he PCI bus. Enabling t he buffer enables t he CPU t o im m ediat ely writ e up t o 4 words of dat a t o t he buffer so t hat it can cont inue on anot her t ask wit hout wait ing for t hose 4 w ords of dat a t o reach t he PCI bus. The dat a in t he writ e buffer will be writ t en t o t he PCI bus w hen t he next PCI bus read cycle st art s. The difference here is t hat it does so wit hout st alling t he CPU for t he ent ire CPU t o PCI t ransact ion. Ther efor e, it 's r ecom m ended t hat you e n a ble t he CPU t o PCI w rit e buffer .

Chipset Feat ures Set up

(Part 6)

PCI D yn a m ic Bu r st in g Opt ion s : Enabled, Disabled This BI OS opt ion cont rols t he PCI w rit e buffer. I f t his is enabled, t hen ev er y w rit e t ransact ion on t he PCI bus goes st raight t o t he w rit e buffer. Burst t ransact ions are t hen sent on t heir way as soon as t her e are enough t o send in a single burst . I f t his opt ion is disabled, t he dat a w ill go t o t he w rit e buffer and burst - t ransferred lat er ( when t he PCI bus is free or when t he buffer is full) if t he writ e t ransact ion is a burst t ransact ion. I f t he writ e t ransact ion is not a burst t ransact ion, t hen t he writ e buffer is flushed and t he dat a is writ t en t o t he PCI bus im m ediat ely. I t is recom m ended t hat you enable PCI D yn a m ic Bur st in g for bet t er PCI perform ance.

PCI M a st e r 0 W S W r it e Opt ion s : Enabled, Disabled This funct ion det erm ines whet her t her e's a delay before any w rit es t o t he PCI bus. I f t his is enabled, t hen writ es t o t he PCI bus ar e execut ed im m ediat ely ( wit h zero wait st at es) , as soon as t he PCI bus is r eady t o r eceive dat a. But if it is disabled, t hen ev ery w rit e t ransact ion t o t he PCI bus is delayed by on e wait st at e. Nor m ally, it 's recom m ended t hat you e n a ble t his for fast er PCI perfor m ance. How ev er, disabling it m ay be useful when ov er clocking t he PCI bus result s in inst abilit y. The delay will generally im prove t he ov er clockabilit y of t he PCI bus.

PCI D e la y Tr a nsa ct ion Opt ion s : Enabled, Disabled This feat ure is sim ilar t o t he Delayed Transact ion BI OS opt ion. I t is used t o m eet t he lat ency of PCI cycles t o and from t he I SA bus. The I SA bus is m uch, m uch slower t han t he PCI bus. Thus, PCI cycles t o and from t he I SA bus t ake a longer t im e t o com plet e and t his slows t he PCI bus down. How ev er, enabling D e la ye d Tr a nsa ct ion enables t he chipset 's em bedded 32- bit post ed writ e buffer t o support delayed t ransact ion cy cles. This m eans t hat t ransact ions t o and fr om t he I SA bus are buffered and t he PCI bus can be fr eed t o perform ot her t ransact ions w hile t he I SA t ransact ion is underw ay.

This opt ion should be e na ble d for bet t er perform ance and t o m eet PCI 2.1 specificat ions. Disable it only if your PCI cards cannot work properly or if y ou ar e using an I SA card t hat is not PCI 2.1 com pliant .

PCI # 2 Acce ss # 1 Re t r y Opt ion s : Enabled, Disabled This BI OS feat ur e is linked t o t he CPU t o PCI Wr it e Buffer. Nor m ally, t he CPU t o PCI Writ e Buffer is enabled. All writ es t o t he PCI bus ar e, as such, im m ediat ely writ t en int o t he buffer , inst ead of t he PCI bus. This frees up t he CPU from wait ing t ill t he PCI bus is free. The dat a ar e t hen w rit t en t o t he PCI bus when t he next PCI bus cy cle st art s. Ther e's a possibilit y t hat t he buffer writ e t o t he PCI bus m ay fail. When t hat happens, t his BI OS opt ion det erm ines if t he buffer w rit e should be reat t em pt ed or sent back for arbit rat ion. I f t his BI OS opt ion is enabled, t hen t he buffer will at t em pt t o writ e t o t he PCI bus unt il successful. I f disabled, t he buffer will flush it s cont ent s and regist er t he t ransact ion as failed. The CPU will have t o w rit e again t o t he w rit e buffer . I t is recom m ended t hat you e na ble t his feat ur e unless you have m any slow PCI devices in your syst em . I n t hat case, disa bling t his feat ur e will prevent t he generat ion of t oo m any ret ries which m ay sev er ely t ax t he PCI bus.

M a st e r Pr ior it y Rot a t ion Opt ion s : 1 PCI , 2 PCI , 3 PCI This feat ure cont rols t he CPU's access t o t he PCI bus. I f y ou choose 1 PCI , t he CPU will always be grant ed access right aft er t he current PCI bus m ast er t r ansact ion com plet es, irrespect ive of how m any ot her PCI bus m ast ers ar e on t he queue. This affords t he quickest CPU access t o t he PCI bus but m eans poor er perform ance for t he PCI bus devices. I f y ou choose 2 PCI , t he CPU will be grant ed access aft er t he current and t he next PCI t ransact ion com plet es. I n ot her words, t he CPU is guarant eed access aft er t wo PCI bus m ast er t r ansact ions, irrespect ive of how m any ot her PCI bus m ast ers ar e also on t he queue. This m eans t he CPU has t o wait a lit t le longer t han wit h t he 1 PCI opt ion but PCI devices will have quicker access t o t he PCI bus. I f y ou choose 3 PCI , t he CPU will only be grant ed access t o t he PCI bus aft er t he curr ent PCI bus m ast er t ransact ion and t he following t wo PCI bus m ast er t ransact ions on t he queue have been com plet ed. So, t he CPU has t o w ait for t hree PCI bus m ast ers t o com plet e t heir t ransact ions on t he PCI bus befor e it can gain access t o t he PCI bus it self. This m eans poor er CPU- t o- PCI perform ance but PCI bus m ast er devices will enj oy bet t er perform ance. But irrespect ive of your choice, t he CPU is guarant eed access t o t he PCI bus aft er a m axim um of 3 PCI m ast er grant s. I t doesn't m at t er if t her e ar e num erous PCI bus

m ast ers on t he queue or when t he CPU r equest ed access t o t he PCI bus. I t will always be grant ed access aft er one PCI bus m ast er t ransact ion ( 1 PCI ) , t w o t ransact ions ( 2 PCI ) or t hree t ransact ions ( 3 PCI ) .

AGP 4 X M ode Opt ion s : Enabled, Disabled This feat ure is only found on m ot herboards t hat support AGP4X. Howev er , it 's usually set t o D isa ble d by default because not ev ery one will be using an AGP4X card wit h t he m ot herboard. For users of AGP1X or 2X cards, t his BI OS opt ion needs t o be disabled for t he cards t o w ork properly. I n order t o prev ent com plicat ions, m anufact urers pr efer t o j ust disable AGP4X m ode. How ev er, t his m eans user s of AGP4X cards will lose out on t he gr eat er bandwidt h afforded by t he AGP4X m ode. While AGP4X m ode's act ual t ransfer rat e isn't significant ly higher t han t hat of AGP2X, it 's st ill a wast e not t o use t he m ode when it 's available. So, if y ou own an AGP4X card, it 's recom m ended t hat you e na ble AGP4X m ode for bet t er AGP perfor m ance. Leav e it as disabled only if you hav e a graphics card t hat can only support AGP1X or AGP2X t ransfer m odes.

Chipset Feat ures Set up

(Part 7)

AGP D r iv ing Cont r ol Opt ion s : Aut o, Manual This BI OS funct ion allows y ou t o adj ust t he cont rol of t he AGP driving for ce. I t is usually set t o Aut o by default , t hereby allowing t he chipset t o assum e cont rol and aut om at ically adj ust t he AGP driving force t o suit t he inst alled AGP card. How ev er, for t r oubleshoot ing or overclocking purposes, y ou can set t he AGP Driving Cont rol t o m anual so t hat you can select t he AGP D r iv in g Va lu e you w ant .

AGP D r iv ing V a lue Opt ion s : 00 t o FF ( Hex num bers) This opt ion is slaved t o t he AGP D r ivin g Cont r ol BI OS funct ion. I f you set t he AGP Driving Cont rol t o Aut o, t hen t he value you set her e w on't have any effect . I n order for t his BI OS opt ion t o work, you need t o set t he AGP Driving Cont rol t o Manual. The AGP D r iv ing V a lu e det erm ines t he signal st rengt h of t he AGP bus. The higher t he value, t he st r onger t he signal. The range of Hex values ( 00 t o FF) t ranslat es int o 0 t o 255 in decim al values. By default , t he AGP Driving Value is set t o D A ( 218) but if you ar e using an AGP card based on t he NVI DI A GeForce2 line of GPUs, t hen it 's recom m ended t hat you set t he AGP Driving Value t o t he higher value of EA ( 234) . Due t o t he nat ure of t his BI OS opt ion, it 's possible t o use it as an aid in ov er clocking t he AGP bus. The AGP bus is sensit ive t o overclocking, especially in AGP4X m ode and wit h sidebanding enabled. As such, a higher AGP Driving Value m ay be j ust what you need t o ov er clock t he AGP higher t han norm ally possible. By raising t he signal st rengt h of t he AGP bus, y ou can im prov e it s st abilit y at ov er clock ed speeds. But be v er y, v ery circum spect when you increase t he AGP Driving Value on an ov er clocked AGP bus as your AGP card m ay be ir r e ve r sibly da m a ge d in t he process! BTW, cont rar y t o som e report s, increasing t he AGP Driving Value w on't im prove t he perform ance of t he AGP bus. I t is n ot a perform ance enhancing opt ion so you shouldn't increase t he v alue unless y ou need t o.

D e la y D RAM Re a d La t ch Opt ion s : Aut o, No Delay, 0.5ns, 1.0ns, 1.5ns This funct ion fine- t unes t he DRAM t im ing t o adj ust for different DRAM loadings. DRAM load changes wit h t he num ber as well as t he t ype of DI MM inst alled. Mor e DI MMs and double- sided DI MMs increase t he DRAM load. As such, a single singlesided DI MM provides t he lowest DRAM load. Wit h heavier DRAM loads, y ou m ay need t o delay when t he chipset lat ches ont o t he DI MMs during reads. Ot herwise, t he chipset m ay fail t o lat ch properly ont o t he DI MMs and read dat a fr om t hem . Nor m ally, you should j ust let t he BI OS t o decide for it self ( using t he Aut o opt ion) . But if you not ice t hat your sy st em has becom e unst able upon inst allat ion of addit ional DI MMs, y ou should t ry m anually set t ing t he DRAM Read Lat ch delay your self. Nat urally, a longer delay decreases perform ance so use t he lowest value t hat resolves t he problem . I f you have a light DRAM load, you can " ensure" it s opt im al perform ance by m anually using t he N o D e la y opt ion. This forces t he chipset t o lat ch ont o t he DI MMs wit hout delay, ev en if t he BI OS t hinks a delay is needed.

M D D r iving St r e ngt h Opt ion s : Hi/ High, Lo/ Low The M D D r iving St r e n gt h det erm ines t he signal st rengt h of t he m em ory dat a line. The higher t he value, t he st ronger t he signal. I t is m ainly used t o boost t he DRAM driving capabilit y wit h heavier DRAM loads ( m ult iple and/ or double- sided DI MMs) . So, if you are using a heavy DRAM load, you should set t his funct ion t o H i or H igh . Due t o t he nat ure of t his BI OS opt ion, it 's possible t o use it as an aid in ov er clocking t he m em or y bus. Your SDRAM DI MM m ay not ov er clock as w ell as you want ed it t o. But by raising t he signal st rengt h of t he m em ory dat a line, it is possible t o im prov e it s st abilit y at overclock ed speeds. But t his is not a sur efire way of ov er clocking t he m em or y bus. I n addit ion, increasing t he m em ory bus signal st rengt h will not im prov e t he perform ance of t he SDRAM DI MMs. So, it 's advisable t o leave t he MD Driving St rengt h at Lo/ Low unless y ou have a high DRAM load or if y ou are t rying t o st abilize an ov erclock ed DI MM.

SD RAM Pa ge Closing Policy Opt ion s : One Bank, All Banks This feat ure is also labeled as SD RAM Pr e ch a r ge Con t r ol in som e BI OSes. This feat ur e det erm ines whet her t he pr ocessor or t he SDRAM it self cont r ols t he precharging of t he SDRAM. I f t his opt ion is set t o All Ba nk s, all CPU cy cles t o t he SDRAM will result in an All Banks Precharge Com m and on t he SDRAM int erface which im proves st abilit y but reduces perform ance. I f t his feat ur e is set t o One Ba nk , precharging is left t o t he SDRAM it self. This reduces t he num ber of t im es t he SDRAM is precharged since m ult iple CPU cy cles t o t he SDRAM can occur before t he SDRAM needs t o be refreshed. So, use One Ba nk for opt im al perform ance unless you ar e facing syst em st abilit y issues wit h t his opt ion.

I nt egrat ed Peripherals

(Part 1)

Onboa r d I D E- 1 Cont r olle r Opt ion s : Enabled, Disabled This opt ion enables you t o act ivat e/ inact ivat e t he first I DE channel of t he m ot herboard's onboard I DE cont r oller. You should leave t his enabled if you are using t his onboard I DE channel. Disabling it will prev ent t he I DE devices at t ached t o t his channel from funct ioning at all. I f y ou are not at t aching any I DE devices t o t his port ( or if you are using a SCSI / ext ernal I DE card inst ead) , you can disable t his I DE channel t o fr ee an I RQ for ot her use.

Onboa r d I D E- 2 Cont r olle r Opt ion s : Enabled, Disabled This opt ion enables you t o act ivat e/ inact ivat e t he second I DE channel of t he m ot herboard's onboard I DE cont r oller. You should leave t his enabled if you are using t his onboard I DE channel. Disabling it will prev ent t he I DE devices at t ached t o t his channel from funct ioning at all. I f y ou are not at t aching any I DE devices t o t his port ( or if you are using a SCSI / ext ernal I DE card inst ead) , you can disable t his I DE channel t o fr ee an I RQ for ot her use.

M a st e r / Sla ve D r ive PI O M ode Opt ion s : 0, 1, 2, 3, 4, Aut o This feat ure is usually found under t he Onboa r d I D E- 1 Con t r olle r or Onboa r d I D E- 2 Con t r olle r opt ion. I t 's linked t o one of t he I DE channels so if y ou disable one, t he cor responding Mast er/ Slave Drive PI O Mode opt ion for t hat I DE channel eit her disappears or is gray ed out . This feat ure allows you t o set t he PI O ( Program m ed I nput / Out put ) m ode for t he t w o I DE devices ( Mast er and Slave drives) at t ached t o t hat part icular I DE channel. Nor m ally, you should leave it as Aut o and let t he BI OS aut o- det ect t he I DE drive's PI O m ode. You should only set it m anually for t he following reasons : •

if t he BI OS cannot det ect t he corr ect PI O m ode

•

if you w ant t o t ry t o run t he I DE device w it h a higher PI O m ode t han it w as designed for

•

if you have ov erclock ed t he PCI bus and one or m or e of your I DE devices cannot funct ion properly ( you can cor r ect t he problem by using a slower PI O m ode)

Not e t hat ov erclocking t he PI O t ransfer rat e can cause loss of da t a . Below is a t able of t he different PI O t ransfer rat es and t heir corr esponding m axim um t hroughput s. PIO Data Transfer Mode Maximum Throughput (MB/s) PIO Mode 0

3.3

PIO Mode 1

5.2

PIO Mode 2

8.3

PIO Mode 3

11.1

PIO Mode 4

16.6

M a st e r / Sla ve D r ive Ult r a D M A Opt ion s : Aut o, Disabled This feat ure is usually found under t he Onboa r d I D E- 1 Con t r olle r or Onboa r d I D E- 2 Con t r olle r opt ion. I t 's linked t o one of t he I DE channels so if y ou disable one, t he corresponding Mast er/ Slave Drive Ult ra DMA opt ion for t hat I DE channel eit her disappears or is greyed out . This feat ure allows you t o enable or disable Ult raDMA support ( if available) for t he t wo I DE devices ( Mast er and Slave drives) at t ached t o t hat part icular I DE channel. Nor m ally, you should leave it as Aut o and let t he BI OS aut o- det ect if t he drive support s Ult raDMA. I f it does, t he proper Ult raDMA t ransfer m ode will be enabled for t hat drive, allowing it t o burst dat a at up t o 100MB/ s. You should only disable it for t roubleshoot ing purposes. Not e t hat set t ing t his t o Aut o does not enable Ult raDMA or any of t he slower DMA m ode for I DE devices t hat do not support Ult raDMA. Also, in order for any of t hose DMA m odes t o work ( including t he Ult raDMA m odes) , y ou will have t o enable DMA t ransfer via t he OS. I n Win9x, t hat can be done by t icking t he D M A checkbox in t he propert ies sheet of t hat I DE drive. Below is a t able of t he different DMA t ransfer rat es and t heir corr esponding m axim um t hroughput s. DMA Transfer Mode Maximum Throughput (MB/s) DMA Mode 0

4.16

DMA Mode 1

13.3

DMA Mode 2

16.6

UltraDMA 33

33.3

UltraDMA 66

66.7

UltraDMA 100

100.0

Ult r a D M A- 6 6 / 1 0 0 I D E Cont r olle r Opt ion s : Enabled, Disabled This opt ion allows y ou t o enable or disable t he e x t r a onboard Ult raDMA 66/ 100 cont r oller ( if available) . This does n ot include t he built - in I DE cont r oller of t he I nt el I CH1 and I CH2 or VI A chipset s which already support Ult raDMA 66/ 100. This funct ion is only for t he e x t r a I DE cont roller ( fr om HighPoint or Pr om ise) t hat has been included onboard t he m ot herboard, in addit ion t o t he built - in I DE cont roller of t he chipset .

I f y ou have one or m ore I DE devices at t ached t o t his Ult raDMA 66/ 100 cont roller, you should enable t his funct ion in order t o be able t o use t hose I DE devices. You should only disable it for t he following reasons : •

if you don't hav e any I DE device at t ached t o t he addit ional Ult raDMA 66/ 100 cont r oller

•

your m ot herboard doesn't have an ext ra Ult raDMA 66/ 100 cont roller onboard

•

for t roubleshoot ing purposes

Not e t hat disabling t his funct ion m ay cut down boot ing t im e. This is because t he I DE cont r oller's BI OS w on't be loaded and t hus t her e w on't be a need t o wait for it t o query for I DE devices on it s I DE channels. So, if y ou don't use it , it m ight be best t o disable it . USB Cont r olle r Opt ion s : Enabled, Disabled This funct ion is sim ilar t o Assign I RQ For USB. I t enables or disables I RQ allocat ion for t he USB ( Universal Serial Bus) . Enable t his if you ar e using a USB device. I f you disable t his while using a USB device, you m ay have problem s running t hat device. How ev er, if y ou don't use any USB devices, set t he opt ion t o D isa ble d. I t will free up an I RQ for ot her devices t o use.

I nt egrat ed Peripherals

(Part 2)

USB Ke yboa r d Suppor t Opt ion s : Enabled, Disabled This funct ion enables or disables support for a USB keyboard. Enable it if you ar e using a USB keyboard. Ot herwise, disable it .

USB Ke yboa r d Suppor t Via Opt ion s : OS, BI OS This opt ion det erm ines whet her t he USB k eyboard is support ed via t he operat ing syst em or t he BI OS. Support via OS offers bet t er funct ionalit y but at t he expense of zero funct ionalit y in DOS. So, if you use real m ode DOS, set t he opt ion t o BI OS so t hat you can use t he USB keyboard in DOS wit hout t he need t o inst all a driver .

I nit D ispla y Fir st Opt ion s : AGP, PCI I f y ou ar e using m or e t han one graphics card, t his funct ion enables you t o select whet her t o use t he AGP graphics card or t he PCI graphics card as t he prim ary graphics card. This is useful for users who inst all m ore t han one graphics card but only use a single m onit or. This will enable t hem t o select whet her t o boot t he sy st em using t he AGP graphics card or t he PCI graphics card. I f y ou are only using one graphics card, t hen t he BI OS will det ect it as such and boot it up as norm al, irrespect ive of what y ou set t he opt ion as. How ev er , t her e m ay be a slight reduct ion in init ializat ion t im e if you set t his funct ion t o it s proper set t ing. That m eans if y ou only use an AGP graphics card, t hen set t ing I nit D ispla y Fir st t o AGP m ay reduce boot - up t im e a lit t le.

KBC I n pu t Clock Se le ct Opt ion s : 8MHz, 12MHz, 16MHz This funct ion allows you t o adj ust t he keyboard clock for bet t er r esponse or t o fix a keyboard pr oblem . You should set it t o 1 6 M H z for a bet t er response t im e. But if t he keyboard becom es errat ic or fails t o init ialize, t r y a lower clockspeed t o fix t hat .

Pow e r On Fu n ct ion Opt ion s : But t on Only, Keyboard 98, Hot Key, Mouse Left , Mouse Right This funct ion allows you t o set t he m et hod by w hich your sy st em can be t urned on. Nor m ally, it should be set as But t on Only so t hat your sy st em will only st art up if you use t he but t on/ sw it ch on t he casing. Ot her alt ernat ive opt ions including st art ing up t he sy st em using t he keyboard ( if it support s t he Keyboard 98 st andard) , a keyboard hot k ey ( for ot her st andard k eyboards) or t he m ouse. Not e t hat only PS/ 2 m ice support t his funct ion and t hen, not all of t hem . Som e PS/ 2 m ice cannot support t his funct ion due t o som e com pat ibilit y problem . Mice using t he COM port and t he USB connect ion w ill also not w ork w it h t his funct ion. The Keyboard 98 opt ion will only work if y ou have inst alled Windows 98 and you have t he appr opriat e k eyboard. Then y ou can use t he k eyboard's wak e- up key t o st art up t he sy st em . Older k eyboards t hat don't have t he special wake- up key can use t he H ot Ke y opt ion inst ead. Ther e ar e t w elve hot keys available : Ct rl- F1 t o Ct rl- F12. Select t he hot key you w ant and you w ill be able t o st art up t he com put er using t hat hot key. How ev er, if y our k eyboard is t oo old, t his funct ion m ay not work . Ther e is no perform ance advant age in choosing any one of t he opt ions abov e so choose one t hat y ou ar e com fort able wit h.

Onboa r d FD D Cont r olle r Opt ion s : Enabled, Disabled This funct ion allows you t o enable or disable t he onboard floppy drive cont roller. I f you are using a floppy drive connect ed t o t he onboard cont roller, t hen leav e it at t he default set t ing of Ena ble d. But if y ou ar e using an add- on FDD cont roller or if you are not using any floppy drive at all, set it t o D isa ble d t o sav e an I RQ.

Onboa r d Se r ia l Por t 1 / 2 Opt ion s : Disabled, 3F8h/ I RQ4, 2F8h/ I RQ3, 3E8h/ I RQ4, 2E8h/ I RQ3, 3F8h/ I RQ10, 2F8h/ I RQ11, 3E8h/ I RQ10, 2E8h/ I RQ11, Aut o This feat ure allows you t o disable t he onboard serial port or t o m anually select t he I / O addr ess and I RQ for it . Norm ally, you should leave it as Aut o so t hat t he BI OS can select t he best set t ings for it but if you need a part icular I RQ t hat 's been t aken up by t his serial port , y ou can m anually select an alt ernat ive I RQ for it . I f you are not using t his serial port , you can also disable it t o save an I RQ.

Onboa r d I R Fu nct ion Opt ion s : I rDA ( HPSI R) m ode, ASK I R ( Am plit ude Shift Keyed I R) m ode, Disabled This feat ure is usually found under t he Onboar d Serial Port 2 opt ion. I t 's linked t o t he 2nd serial port so if y ou disable t he 2nd serial port , t his feat ure will disappear fr om t he scr een or appear gr ayed out . Ther e ar e t wo differ ent I R ( I nfra- Red) m odes. Choose t he one appropriat e for t he connect ion t o t he ext ernal device. Not e t hat t his feat ure requires an I R connect or t o be plugged int o t he I R header provided on t he m ot herboard.

D uple x Se le ct Opt ion s : Full- Duplex, Half- Duplex This feat ure is usually found under t he Onboar d Serial Port 2 opt ion. I t 's linked t o t he 2nd serial port so if y ou disable t he 2nd serial port , t his feat ure will disappear fr om t he scr een or appear gr ayed out . This feat ure allows you t o det erm ine t he t ransm ission m ode of t he I R port . Select ing Fu ll- D u ple x will perm it sim ult aneous t wo- way t ransm ission, like a conversat ion ov er t he phone. How ev er, select ing H a lf- D u ple x per m it s t ransm ission in one direct ion at any one t im e only. Thus, t he Full- D u ple x m ode is fast er and m uch m ore desirable. How ev er, consult your I R peripheral's m anual t o det erm ine if Full- D uple x is support ed or not .

Rx D , Tx D Act iv e Opt ion s : High, Low This feat ure is usually found under t he Onboar d Serial Port 2 opt ion. I t 's linked t o t he 2nd serial port so if y ou disable t he 2nd serial port , t his feat ure will disappear fr om t he scr een or appear gr ayed out . This feat ure enables you t o set t he I R recept ion/ t ransm ission polarit y as H igh or Low . You'll need t o consult your I R peripheral's docum ent at ion t o det erm ine t he corr ect polarit y.

I nt egrat ed Peripherals

(Part 3)

On boa r d Pa r a lle l Por t Opt ion s : 3BCh/ I RQ7, 278h/ I RQ5, 378h/ I RQ7, Disabled This funct ion allows you t o select t he I / O address and I RQ for t he onboard parallel port . The default I / O address of 378h and I RQ of 7 should work w ell in m ost cases so unless you have a pr oblem , you should j ust leave it at t he default set t ings. Only select an alt ernat ive I / O address or I RQ if you are facing configurat ion problem s wit h t he parallel port .

Pa r a lle l Por t M ode Opt ion s : ECP, EPP, ECP+ EPP, Norm al ( SPP) This feat ure is usually found under t he Onboar d Parallel Port opt ion. I t 's linked t o t he parallel port so if you disable t he parallel port , t his feat ure will disappear from t he scr een or appear gr ey ed out . Ther e ar e four opt ions. The default value is N or m a l ( SPP) which will work wit h all parallel port devices but is very slow. Tw o fast er bidirect ional m odes are available, nam ely t he ECP ( Enhanced Com Port ) and EPP ( Enhanced Parallel Port ) m odes. ECP uses t he DMA prot ocol t o achiev e dat a t ransfer rat es of up t o 2.5Mbit s/ s and provides sym m et ric bidirect ional com m unicat ion. On t he ot her hand, EPP uses exist ing parallel port signals t o provide asym m et ric bidirect ional com m unicat ion. Generally, because of it s FI FOs and t he DMA channel it uses, ECP is good for large dat a t ransfer s ( useful for scanner s and print ers) . On t he ot her hand, EPP is bet t er wit h links t hat swit ch direct ions fr equent ly ( like parallel port drives) . This t ip was obt ained from Jan Ax elson's Parallel Port FAQ so check it out if you r equire m or e inform at ion on parallel port s. How ev er, t he m anufact urer of y our parallel port peripheral m ay hav e designat ed a preferred parallel port m ode. I n t hat case, it 's best t o follow t heir recom m endat ions. For t hose who don't know what m ode t o select but at least know t hat t heir parallel port device support s bi- direct ional t ransfers, t he BI OS offers t he ECP+ EPP m ode. I f you select t his m ode, t hen t he parallel port device will be able t o use eit her one of t hose m odes. How ev er , t his should be considered as a last r esort as you m ay be needlessly t ying up an I RQ for not hing ( if your device does not use ECP at all) or your BI OS m ay not select t he best parallel port m ode for t he device. I f possible, set t he parallel port t o t he t ransfer m ode t hat best suit s your parallel port device.

ECP M ode Use D M A Opt ion s : Channel 1, Channel 3 This feat ure is usually found under t he Parallel Port Mode opt ion. I t 's linked t o t hat opt ion so if y ou did not enable eit her t he ECP or ECP+ EPP m ode, t his feat ur e will disappear from t he screen or appear gray ed out . You can use t his feat ure t o select t he DMA channel of your preference. Norm ally, t he default value of DMA Channel 3 will work j ust fine. You should only select t he alt ernat ive value of Channel 1 if t here's a conflict wit h anot her device.

EPP M ode Se le ct Opt ion s : EPP 1.7, EPP 1.9 This feat ure is usually found under t he Parallel Port Mode opt ion. I t 's linked t o t hat opt ion so if y ou did not enable eit her t he EPP or ECP+ EPP m ode, t his feat ur e will disappear from t he screen or appear gray ed out . You can use t his feat ure t o choose w hich version of EPP t o use. I couldn't find anyt hing on t he difference bet w een version 1.7 and 1.9 but an educat ed guess would be t hat v ersion 1.9 w ould be fast er/ bet t er t han version 1.7. So, for w ant of bet t er inform at ion, I can only recom m end t hat you select EPP 1 .9 if possible but st ep dow n t o EPP 1 .7 if your device appears t o be having som e problem w it h t he connect ion.

PNP/ PCI Configurat ion PN P OS I nst a lle d Opt ion s : Yes, No I f all your operat ing syst em s support Plug & Play ( PnP) , select Ye s so t hat t hey can t ake ov er t he m anagem ent of device resources. I f you are using a non- PnP- aw are OS or not all of t he oper at ing syst em s y ou are using support PnP, select N o t o let t he BI OS handle it inst ead. Not e t hat Windows 2000 w ill work wit h ACPI even wit h Pn P OS I n st a lle d set t o Ena ble d . Just m ake sur e y ou disable Adv a nce d Pow e r M a n a ge m e nt ( APM ) . This inform at ion was cont ribut ed by Alex. For m or e inform at ion, check out his e- m ail. Alex also provided a link t o a Microsoft art icle on how t o set up ACPI support for Windows 98 users ( Unfort unat ely, t his link is broken. I f y ou find t his art icle, do let m e know so t hat I can m irr or it .) . How ev er, Micr osoft recom m ends t hat you disable PnP OS I nst alled, j ust t o be safe. Here's t he link t o t he Micr osoft art icle on I RQ sharing in Windows 2000 provided by Ryu Connor. For Linux users, Jonat han has t he following advice Alt hough Linux is not really PnP com pat ible, m ost dist ribut ions use a piece of soft ware called I SAPNPTOOLS t o set up I SA cards. I f y ou have PnP OS set t o No, t he BI OS will at t em pt t o configure I SA cards it self. This does not m ak e t hem work wit h Linux, t hough, you st ill need t o use som et hing like I SAPNPTOOLS. How ever, having bot h t he BI OS and I SAPNPTOOLS at t em pt ing t o configure I SA cards can lead t o problem s wher e t he t w o don't agree. The solut ion? Set PnP OS t o Yes, and let I SAPNPTOOLS t ake care of I SA cards in Linux, as BI OS configurat ion of I SA cards doesn't w ork for Linux anyw ay ( w it h t he curr ent st able and developm ent k ernels) . Most t im es, it probably won't m ake a difference, but som eone som ewher e will have problem s, and Linux will always work wit h PnP OS set t o Yes. Please refer t o Com m ent s # 80 and # 82 for m or e inform at ion on Linux and PnP.

For ce Upda t e ESCD / Re se t Configur a t ion D a t a Opt ion s : Enabled, Disabled ESCD ( Ext ended Syst em Configurat ion Dat a) is a feat ure of t he Plug & Play BI OS t hat st or es t he I RQ, DMA, I / O and m em or y configurat ions of all t he I SA, PCI and AGP cards in t he syst em ( PnP or ot herwise) . Norm ally, you should leave t he set t ing as D isa ble d. But if you have inst alled a new add- on card and t he consequent syst em reconfigurat ion causes a serious conflict of resources ( t he OS m ay not boot as a result ) , t hen you should enable it so t hat t he BI OS will reset and r econfigure t he

set t ings for all PnP cards in t he syst em during boot up. The BI OS will aut om at ically reset t he set t ing t o D isa ble d t he next t im e you boot .

Re sour ce Cont r olle d By Opt ion s : Aut o, Manual The BI OS has t he capabilit y t o aut om at ically configure all of t he boot and Plug & Play com pat ible devices. Nor m ally, you should set it as Aut o, so t hat t he BI OS can aut om at ically assign t he I RQs and DMA channels. All t he I RQ and DMA assignm ent fields should disappear as a result . But if you are facing problem s assigning t he resources aut om at ically via t he BI OS, you can select M a nu a l t o rev eal t he I RQ and DMA assignm ent fields. Then you can assign each I RQ or DMA channel t o eit her Legacy I SA or PCI / I SA PnP devices. Legacy I SA devices ar e com pliant wit h t he original PC AT bus specificat ion and require a specific int err upt / DMA channel t o funct ion properly. PCI / I SA PnP devices, on t he ot her hand, adhere t o t he Plug & Play st andard and can use any int errupt / DMA channel.

Assign I RQ For V GA Opt ion s : Enabled, Disabled Many high- end graphics accelerat or cards now require an I RQ t o funct ion properly. Disabling t his feat ure wit h such cards will cause im proper oper at ion and/ or poor perform ance. Thus, it 's best t o m ake sure you enable t his feat ure if you are having problem s wit h your graphics accelerat or card. How ev er, som e low - end cards don't need an I RQ t o run norm ally. Check your graphics card's docum ent at ion ( m anual) . I f it st at es t hat t he card does not require an I RQ, t hen you can disable t his feat ure t o release an I RQ for ot her uses. When in doubt , it 's best t o leav e it enabled unless you really need t he I RQ.

Assign I RQ For USB Opt ion s : Enabled, Disabled This funct ion is sim ilar t o USB Cont r olle r . I t enables or disables I RQ allocat ion for t he USB ( Universal Serial Bus) . Enable t his if you ar e using a USB device. I f you disable t his while using a USB device, you m ay have problem s running t hat device. How ev er, if y ou don't use any USB devices, set t he opt ion t o D isa ble d. I t will free up an I RQ for ot her devices t o use.

PCI I RQ Act iva t e d By Opt ion s : Edge, Lev el This is a rarely seen BI OS feat ur e t hat allows you t o set t he m et hod by which t he I RQs for y our PCI cards are act ivat ed / t riggered. I SA and old PCI cards are Edge t riggered ( using a single v olt age) while newer PCI and AGP cards are Le ve l t riggered ( using m ult iple volt age lev els) . When PCI devices w ere j ust int roduced, t he set t ing t hat every one was asked t o use was Edge because no PCI device back t hen support ed I RQ sharing. Howev er , now t hat alm ost ev ery PCI device support s I RQ shar ing and I RQs are usually in short age, it 's best t o set it as Le v e l so t hat your PCI devices can shar e I RQs. So, set it t o Le ve l unless y ou are using old edge- t riggered PCI cards.

PI RQ_ 0 Use I RQ N o. ~ PI RQ_ 3 Use I RQ N o. Opt ion s : Aut o, 3, 4, 5, 7, 9, 10, 11, 12, 14, 15 This feat ure allows you t o m anually set t he I RQ for a part icular device inst alled on t he AGP and PCI bus. This is especially useful when y ou ar e t ransfer ring a hard disk from one com put er t o anot her; and you don't w ant t o reinst all your OS t o redet ect t he I RQ set t ings. So, by specifying t he I RQ for t he devices t o fit t he original set t ings, you can circum vent a lot of configurat ion problem s aft er inst alling t he hard disk in a new syst em . N ot e s : •

I f y ou specify a part icular I RQ here, y ou can't specify t he sam e I RQ for t he I SA bus. I f you do, you w ill cause a hardw are conflict .

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Each PCI slot is capable of act ivat ing up t o 4 int errupt s - I NT A, I NT B, I NT C and I NT D

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The AGP slot is capable of act ivat ing up t o 2 int errupt s - I NT A and I NT B

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Nor m ally, each slot is allocat ed I NT A. The ot her int errupt s ar e t here as reserv es in case t he PCI / AGP device requires m or e t han one I RQ or if t he I RQ request ed has been used up.

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The AGP slot and PCI slot # 1 shar e t he sam e I RQs

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PCI slot # 4 and # 5 shar e t he sam e I RQs

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USB uses PI RQ_4

Below is a t able showing t he relat ions bet ween PI RQ and I NT : AGP Slot PCI Slot 4 Signals PCI Slot 2 PCI Slot 3 PCI Slot 1 PCI Slot 5 PIRQ_0

INT A

INT D

INT C

INT B

PIRQ_1

INT B

INT A

INT D

INT C

PIRQ_2

INT C

INT B

INT A

INT D

PIRQ_3

INT D

INT C

INT B

INT A

You will not ice t hat t he int errupt s are st aggered so t hat conflict s do not happen easily. St ill, because t he AGP slot and PCI slot 1 shar e t he sam e set of I RQs, it 's best t o only use eit her one of t hose t w o slot s unless you don't have ot her slot s t o use. The sam e goes for PCI slot 4 and 5. Nor m ally, you should j ust leave it as AUTO. But if you need t o assign a part icular I RQ t o a device on t he AGP or PCI bus, here's how you can m ake use of t his BI OS feat ure. First of all, check out which slot t he device is locat ed in. Then, check t he t able above t o det erm ine which is it s prim ary PI RQ. For ex am ple, if you have a PCI net work card in PCI slot 3, t he t able shows t hat it s prim ary PI RQ is PI RQ_2 because all slot s are first allocat ed I NT A if possible. Aft er t hat , select t he I RQ y ou w ant t o use for t hat slot by assigning it t o t he appropriat e PI RQ. I f t he net work card ( in t he ex am ple above) r equires I RQ 7, t hen set PI RQ_2 t o use I RQ 7. The BI OS will t hen allocat e I RQ 7 t o PCI slot 3. I t 's t hat easy! :) Just rem em ber t hat t he BI OS will t ry t o allocat e t he PI RQ linked t o I NT A for each slot . So, t he AGP slot 's and PCI slot 1's prim ary PI RQ is PI RQ_0 while PCI slot 2's prim ary PI RQ is PI RQ_1 and so on. I t 's j ust a m at t er of linking t he I RQ you want t o t he correct PI RQ for t hat slot .

The BI OS Opt im izat ion Guide r e v. 5 .8 Re vision H ist or y

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