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What is BIOS

All computer hardware has to work with software through an interface. The BIOS gives the computer a little built-in starter kit to run the rest of softwares from floppy disks (FDD) and hard disks (HDD). The BIOS is responsible for booting the computer by providing a basic set of instructions. It performs all the tasks that need to be done at start-up time: POST (Power-On Self Test, booting an operating system from FDD or HDD). Furthermore, it provides an interface to the underlying hardware for the operating system in the form of a library of interrupt handlers. For instance, each time a key is pressed, the CPU (Central Processing Unit) perform an interrupt to read that key. This is similar for other input/output devices (Serial and parallel ports, video cards, sound cards, hard disk controllers, etc...). Some older PC's cannot co-operate with all the modern hardware because their BIOS doesn't support that hardware. The operating system cannot call a BIOS routine to use it; this problem can be solved by replacing your BIOS with an newer one, that does support your new hardware, or by installing a device driver for the hardware.

In order to change the BIOS settings, you must first access the CMOS Setup
When the system is powered on, the BIOS will perform diagnostics and initialize system components, including the video system. (This is self-evident when the screen first flicks before the Video Card header is displayed). This is commonly referred as POST (Power-On Self Test). Afterwards, the computer will proceed its final boot-up stage by calling the operating system. Just before that, the user may interrupt to have access to SETUP. Usually, setup can be entered by pressing a special key combination (DEL, ESC, CTRL-ESC, or CTRL-ALT-ESC) at boot time (Some BIOSes allow you to enter setup at any time by pressing CTRL-ALT-ESC). The AMI BIOS is mostly entered by pressing the DEL key after resetting (CTRL-ALT-DEL) or powering up the computer. You can bypass the extended CMOS settings by holding the key down during boot-up. This is really helpful, especially if you bend the CMOS settings right out of shape and the computer won't boot properly anymore.

Once the bios setup menu has been accessed, you want to try to look for things that can be figured out using common sense; Such as "internal cache --enabled? -- you bet!", or System speed "fast/slow? -- doh!" It really can be that simple. Other things to look for are wait states -- set them as low as possible, video shadow -- enabled. Note, however, that you should try changing only one of these at a time. Change one, note the effect, and if it doesn't cause any problsms with your software then change another, and so on.

Benchmarking can be useful in BIOS setting 'tweaking' as well. When you change a BIOS setting, how do you know if it truly increased the performance at all? By using a benchmark before the setting change, and again after the change, you can determine whether the performance went up, down, or stayed relatively the same. Choose the benchmark that suits you best. 3D-Bench works well, as does Chris's 3D-Benchmark or Norton SI for Win95. For memory timing changes (read/write timing, i.e. 3-1-1-1 to 2-1-1-1), Cachechk v4.0 works nicely as it primarily tests dram timing and does not rely heavily on raw CPU power.

Finally, if after you have fiddled with the BIOS setup options your system freezes up or acts strangely, don't panic! Simply enter the setup program the same way you did the first time and change the settings back to normal. One last point -- don't change anything concerning the hard drive type as you won't be able to reboot the computer until the correct type is reentered.

Turbo Frequency - Enabled (only on 66mhz and 100mhz bus)
Multiplier Factor - CPU default
SEL 100/66# Signal - Set LOW
AGPCLK/CPUCLK - Safest setting is 1/1
L2 cache Latency - As low as possible
Speed Error Hold - Enable in case of errors
CPU Power Supply - User Define, anywhere from 2.0v to 2.3 depending on power supply

Virus Warning - Enable
CPU Level 1 Cache - Enable
CPU Level 2 Cache - Enable
CPU L2 Cache ECC Checking - Disable
Quick Power On Self Test - Enable
Boot Sequence - C,A,SCSI is fastest, doesn't really matter whatever suits you best
Swap Floppy Drive - Disable
Boot Up Floppy Seek - Disable
IDE HDD Block Mode - Enable
PCI/VGA Palette Snoop - Disable, unless video card manual says
Delay for HDD - 0
Video BIOS Shadow - Disable
Shadow address ranges Disable as default

SDRAM CAS Latency Time - 2, if unstable use 3
SDRAM Precharge Control - Enable
DRAM Date Integrity Mode - Non-ECC, if you are using ECC memory enable ECC
System BIOS Cacheable - Disable
Video BIOS Cacheable - Disable
Video RAM Cacheable - Disable
8 Bit I/O Recovery Time - 1
16 Bit I/O Recovery Time - 1
Memory Hole At 15M-16M - Disable
Passive Release - Enable
Delayed Transaction - Enable

Disclaimer -- We, at Mr Tweaks, will not be held responsible for any damage to anything seemingly caused by our advice in this article! This help is provided as a service to you, but common sense must be used when attempting to change settings that you are unfamiliar with. Most likely, the worst that can happen is you could change the hard drive type as reported to the bios which will prevent the system from being booted until the data is reentered, however I am not familiar with all bios settings and therefore there may be some that could cause damage.

When your computer starts up either hold the DEL key or when you see a message saying change setting or something similar to that press DEL. Now we are in the bios, you should see a blue screen with a few menu options. The options are in order as they appear in my bios, but you may have to search around for them, they also may have a slightly different name to below, good luck
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