Either the battery has become corrupt from wearing out over
time, static electricity, the motherboard is bad or the batter is not seated
properly. Another cause can be an improperly install hard drive where the
cables are reversed.
The cmos - checksum bad – error can also happen if you
have tried to clear the cmos and did not properly reinstall the battery.
The first place to check would be the battery on the
motherboard. Remove the case and make sure the motherboard battery is
seated properly in its housing. The try and reboot the computer again.
If you still get the cmos - checksum bad – error, it
may be time to replace the cmos battery.
For this you may have to call your motherboard
manufacturer or the maker of your computer. Once you find a new battery,
replace the old one and see if that does the trick.
If you are still having problems after reseating the
battery, make sure the hard drive cables are installed properly. Sometimes
this can cause the cmos - checksum bad – error.
If none of the above works then you may need to replace
your motherboard. Motherboards can and do go bad. If you are unsure of how
to do this it may be time to call an expert.
Another thing you can check is to make sure your cpu is
set to the proper speed in the bios.
Sometimes this error can happen if these settings are
off. Check your memory settings also to make sure the memory is reading
properly in the system cmos.
For advanced user: You can also reset the system bios
to the default settings and see if that works.
The cmos -
checksum bad – error is most often caused by the battery on the
motherboard. However this is not always the case. It is important to
follow a few steps before determining exactly what is causing the problem.
