Let me try to explain in better detail.
All Motherboards have what is called a BIOS chip, it stands for Basic In/Out System.
The BIOS is a firmware that is burned into an IC chip, it has two layers, one being ROM which stands for Read Only Memory, this is a non-volatile memory area, which under normal conditions can not be changed.
Then you have an EPROM section of memory which is programable and changeable by both the operating system and the systems owner (which is you).
The ROM section can only be changed by using a special program that is designed to FLASH (over-write) this section of memory. There is another part of memory that is rarely touched even with this proceedeure, which makes the system recoverable in the event a bad flash happens.
The EPROM section is the one that allows you and your operating system to make changes to allow hardware to become active as the computer executes its Power On Self Test (POST).
Once the system takes inventory of its hardware, it searches for a boot.ini file, once one is found, it passes control over to that command, which eventually loads your operating system.
Sometimes a user setting in the programable section of the EPROM can have an incorrect setting, which prevents a piece of hardware from functioning correctly once windows tries to take control of it.
There are two options a motherboard manufacture embedded into the BIOS to correct this problem.
Option # 1 is a setting in the main BIOS menu called LOAD SYSTEM DEFAULTS this option resets the BIOS to its unaltered factory settings. This same option is sometimes worded differently in other BIOSes as USE SETUP DEFAULTS.
Option # 2 Is a motherboard manfacture installs a feature called CLR CMOS, this involves safely shorting out the EPROM to system GROUND (which is harmless) and clearing all user settings back to factory defaults. The EPROM section of the BIOS is just like RAM, it needs a constant voltage supply to store the memory settings, this is why you need what is called a CMOS battery, it keeps the memory alive once the system is powered off, it stores your computers TIME and user settings.
The purpose of shorting the CLR CMOS pins is because capacitors which are used through-out your motherboard act as batteries and store voltages, even after the battery is removed, shorting out the CLR CMOS jumper, harmlessly discharges those capacitors and thus completely clears any and all possible CMOS settings.
Once this proceedure is done, the jumper is again placed in its nautral position, the battery is properly placed back into its holder and the system is powered back on. You have to enter the BIOS setup utility to set the correct DATE and TIME, as those were reset back to factory defaults.
you also have to make sure the BIOS redetects your harddrives, there may be a special menu called DETECT HARD DRIVES, which you just allow the system to choose based on what info it detects from the hardrives onboard ROM chip.
Make sure you have PLUG AND PLAY OPERATING SYSTEM INSTALLED? selected as YES, this way Windows has 100% control over which IRQs are used for your hardware and which memory addresses are used for your hardware's I/O addresses.
Long story short, using the CLR CMOS feature is safe to use.
Flashing your BIOS chip with a DOS related Flashing utility can sometimes fail and rewrite the ROM with corrupted data. (But if it doesn't fail, this proceedure can actually correct a corrupted BIOS with a more stable image)
I strongly suggest if you need a BIOS upgrade, if you choose to do it yourself, you do a lot of reading on the subject and follow any instructions your motherboard manuals say to do to to complish this.
Also I would recomend only using their flash utility and their recomended firmware!
Hope this info helps you.
Edited by MrBruce1959, 20 March 2010 - 01:11 PM.