http://www.rojakpot.com/Speed_Demonz/BIOS_Guide/BIOS_Guide_Index.htm
BIOS Features Setup
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
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
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
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
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/EXTC, A, SCSI/EXTC, CD-ROM, ACD-ROM, C, AD, 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, CSCSI/EXT, C, AA, SCSI/EXT, CLS/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.
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
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
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
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
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
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.
Gate A20 Option
Options : Normal, Fast
This feature determines how Gate A20 is used to address memory above 1MB. When this option is set to Fast, the motherboard chipset controls the operation of Gate A20. But when set to Normal, a pin in the keyboard controller controls Gate A20. Setting Gate A20 to Fast improves memory access speed and thus, overall system speed, especially with OS/2 and Windows.
This is because OS/2 and Windows enter and leave protected mode via the BIOS a lot so Gate A20 needs to switch often from enabled to disabled and back again. Setting this feature to Fast improves memory access performance above 1MB because the chipset is much faster in switching Gate A20 than the keyboard controller. It is recommended that you set it to Fast for faster memory accesses.
IDE HDD Block Mode
The IDE HDD Block Mode feature speeds up hard disk access by transferring data from multiple sectors at once instead of using the old single sector transfer mode. When you enable it, the BIOS will automatically detect if your hard disk supports block transfers and configure the proper block transfer settings for it. Up to 64KB of data can be transferred per interrupt with IDE HDD Block Mode enabled. Since virtually all hard disks now support block transfers, there is normally no reason why IDE HDD Block Mode should not be enabled.
However, if you are running WinNT, beware. According to Chris Bope, Windows NT does not support IDE HDD Block Mode and enabling IDE HDD Block Mode can cause corrupted data. Ryu Connor confirmed this by sending me a link to a Microsoft article about Enhanced IDE operation under WinNT 4.0. According to this article, IDE HDD Block Mode (and 32-bit Disk Access) had been observed to cause data corruption in some cases. Microsoft recommends that WinNT 4.0 users disable IDE HDD Block Mode.
If you disable IDE HDD Block Mode, only 512 bytes of data can transferred per interrupt. Needless to say, that degrades performance quite a bit. So, only disable IDE HDD Block Mode if you are running WinNT. Other than that, you should enable it for optimal performance.
For more detailed information on IDE HDD Block Mode, check out our Speed Demonz' guide on IDE Block Mode!
32-bit Disk Access
32-bit Disk Access is a misnomer because it doesn't really allow 32-bit access to the hard disk. What it actually does is set the IDE controller to combine two 16-bit reads from the hard disk into a single 32-bit double word transfer to the processor. This makes more efficient use of the PCI bus as fewer transactions are needed for the transfer of a particular amount of data.
However, according to a Microsoft article about Enhanced IDE operation under WinNT 4.0, 32-bit disk access can cause data corruption under WinNT in some cases. Microsoft recomments that WinNT 4.0 users disable 32-bit Disk Access.
If disabled, data transfers from the IDE controller to the processor will then occur only in 16-bits. This degrades performance, of course, so you should enable it if possible. Disable it only if you face the possibility of data corruption.
You can also find more information on the WinNT issue above in our Speed Demonz' guide on IDE Block Mode!
Typematic Rate Setting
This feature enables you to control the keystroke repeat rate when you depress a key continuously. When enabled, you can manually adjust the settings using the two typematic controls (Typematic Rate and Typematic Rate Delay). If disabled, the BIOS will use the default setting.
Typematic Rate (Chars/Sec)
Options : 6, 8, 10, 12, 15, 20, 24, 30
This is the rate at which the keyboard will repeat the keystroke if you press it continuously. This setting will only work if Typematic Rate Setting is Enabled.
Typematic Rate Delay (Msec)
Options : 250, 500, 750, 1000
This is the delay, in milliseconds, before the keyboard automatically repeats the keystroke that you have pressed continuously. This setting will only work if Typematic Rate Setting is Enabled.
Security Setup
Options : System, Setup
This option will only work once you have created a password through PASSWORD SETTING out in the main BIOS screen.
Setting this option to System will set the BIOS to ask for the password each time the system boots up.
If you choose Setup, then the password is only required for access into the BIOS setup menus. This option is useful for system adminstrators or computer resellers who just want to keep novice users from messing around with the BIOS. :)
PCI/VGA Palette Snoop
This option is only useful if you use an MPEG card or an add-on card that makes use of the graphics card's Feature Connector. It corrects incorrect colour reproduction by "snooping" into the graphics card's framebuffer memory and modifying (synchronizing) the information delivered from the graphics card's Feature Connector to the MPEG or add-on card. It will also solve the problem of display inversion to a black screen after using the MPEG card.
Assign IRQ For VGA
Many high-end graphics accelerator cards now require an IRQ to function properly. Disabling this feature with such cards will cause improper operation and/or poor performance. Thus, it's best to make sure you enable this feature if you are having problems with your graphics accelerator card.
However, some low-end cards don't need an IRQ to run normally. Check your graphics card's documentation (manual). If it states that the card does not require an IRQ, then you can disable this feature to release an IRQ for other uses. When in doubt, it's best to leave it enabled unless you really need the IRQ.
MPS Version Control For OS
Options : 1.1, 1.4
This option is only valid for multiprocessor motherboards as it specifies the version of the Multiprocessor Specification (MPS) that the motherboard will use. The MPS is a specification by which PC manufacturers design and build Intel architecture systems with two or more processors.
MPS version 1.4 added extended configuration tables to improve support for multiple PCI bus configurations and improve future expandability. It is also required for a secondary PCI bus to work without the need for a bridge. Newer versions of server operating systems will generally support MPS 1.4 and as such, you should change the BIOS Setup from the default of 1.1 to 1.4 if your operating system supports version 1.4. Leave it as 1.1 only if you are running older server OSes.
Eugene Tan informed me that the setting for WinNT should be 1.4.
64MB"OS Select For DRAM > 64MB
Options : OS/2, Non-OS/2
When the system memory is more than 64MB in size, OS/2 differs from other operating systems (OS) in the way it manages the RAM. So, for systems running IBM's OS/2 operating system, select OS/2 and for systems running other operating systems, select Non-OS/2.
HDD S.M.A.R.T. Capability
This option enables/disables support for the hard disk's S.M.A.R.T. capability. The S.M.A.R.T. (Self Monitoring Analysis And Reporting) technology is supported by all current hard disks and it allows the early prediction and warning of impending hard disk disasters. You should enable it so that S.M.A.R.T. aware utilities can monitor the hard disk's condition. Enabling it also allows the monitoring of the hard disk's condition over a network. There's no performance advantage in disabling it even if you don't intend to use the S.M.A.R.T. technology.
However, there's a possibility that enabling S.M.A.R.T. may cause spontaneous reboots in networked computers. Johnathan P. Dinan mentioned such an experience with S.M.A.R.T. enabled. S.M.A.R.T. may be sending packets of data through the network even though there's nothing monitoring those data packets. This may have caused the spontaneous reboots that he had experienced (Comment #103). So, try disabling HDD S.M.A.R.T. Capability if you experience reboots or crashes while you are on a network.
Report No FDD For Win95
If you are using Windows 95/98 without a floppy disk drive, select Enabled to release IRQ6. This is required to pass Windows 95/98's SCT test. You should also disable the Onboard FDC Controller in the Integrated Peripherals screen when there's no floppy drive in the system. If you set this feature to Disabled, the BIOS will not report the missing floppy drive to Win95/98.
Delay IDE Initial (Sec)
Options : 0, 1, 2, 3, ..., 15
The booting process of new BIOSes is much faster these days. Thus, some IDE devices may not be able to spin up fast enough for the BIOS to detect them during the booting up process. This setting is used to delay the initialization of such IDE devices during the booting up process.
Leave it at 0 if possible for faster system booting. But if one or more of your IDE devices fail to initialize while booting, increase the value of this setting until they all initialize properly.
Video BIOS Shadowing
When this feature is enabled, the Video BIOS is copied to the system RAM for quicker access. Shadowing improves the BIOS' performance because the BIOS can now be read by the CPU through the 64-bit DRAM bus as opposed to the 8-bit XT bus. This seems quite attractive since that's at least a 100x increase in transfer rate and the only price is the loss of some system RAM which is used to mirror the ROM contents.
However, modern operating systems bypass the BIOS completely and access the graphics card's hardware directly. So, no BIOS calls are made and no benefit from BIOS shadowing is realised. In light of this, there's no use in wasting RAM just to shadow the Video BIOS when it's not used at all.
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