CMOS Checksum error

Posted on 2000-03-06
Last Modified: 2010-04-26
I know what a checksum error is, but what is the significance of getting a "CMOS checksum error" when booting the computer.
Pressing F1 allows machine to continue booting.
Incidentally if I access the BIOS settings, and then exit having saved, the checksum error disappears for the next boot.
Can anybody help? Is BIOS perhaps corrupted, or could it be motherboard?
Question by:MTindill
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LVL 63

Accepted Solution

SysExpert earned 50 total points
ID: 2588558
It means that your NVRAM battery is probably getting old. Have you noticed that the clock is not accurate also. What happens is that there is a checksum on all the Non-volatile CMOS ram, and if does not match the stored value you get the error message. The usual cause is the Motherboard battery. Saving the CMOS settings restes the checksum until next time. I hope this answers your question.
LVL 49

Expert Comment

ID: 2589437
As per SysExpert

It's your battery.  Time settings may not change but other settings may change because of lack of battery power.  The problem is probably occurring when the computer is left overnight and the battery doesn't have enough grunt.

You are fixing the problems and rebooting and the battery does not have to do any work hence no CMOS problems.

Expert Comment

ID: 2591916
The battery is easy to check.  Use a multi-meter, look at the battery for the correct voltage and test with the computer off.  If it's an old system, you may have a dallas chip on the board, they last about 5-6 years.
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Expert Comment

ID: 2595427
If your battery is ok, what bios is on your board(eg award / ami etc...)? Have you tried clearing your cmos and saving it with bios defaults? If you do a soft reset (ie ctrl+alt+del) do you still get the error? If not there could be a fault with the nvram or power supply.

Expert Comment

ID: 2596638
You can replace you battery pretty easily.  Buy a new battery - most boards the battery looks like a nickel now, slip it out and slip the new one in.  Older boards you need to remove the board and desolder the battery and solder the new one in.  NO PROBLEM!

Author Comment

ID: 2605332
Okay, thanks sysexpert, you got there first.
Is there a possibility this problem with the battery would cause a printer not to function at all?
LVL 63

Expert Comment

ID: 2605421
Possible but not probable. If the default value for the printer port gets messed up it could possibly cause the printer not to function. Get a new battery and see if it solves the problem.

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