Reference number: CH000237

CMOS checksum error.

Issue:

CMOS checksum error.

Cause:

This issue is caused when the CMOS values are incorrect. This issue can occur because of any of the below possibilities.

1. Bad or old CMOS battery.
2. BIOS update.
3. Disconnecting power from computer without shutting down computer

Solution:

Bad or old CMOS battery

Attempt to reboot the computer. If error still occurs after rebooting the computer enter CMOS setup and check all values, this includes verifying the time and date are correct. Once everything has been verified and/or changed make sure you save and exit CMOS setup.

If everything appears to be correct and the issue persists try resetting the CMOS values to the defaults and/or Reset Configuration Data. Additional information about how to do this can be found on document CH000976.

Note: If this issue continues to occur after you turn off your computer off it is possible that the CMOS battery may be failing or already bad. Before considering replacing the CMOS battery try leaving your computer on for several days. Additional information about replacing the CMOS battery can be found on document CH000239.

Computer improperly turned off

If the computer was had the power disconnected while it was still running it is possible this could cause the CMOS to become corrupt. Ensure that the computer is ready to be shut off before turning off the computer. If you have a laptop computer ensure that the battery is charged before disconnecting the power connection. 

If the CMOS values have become corrupted entering the values in CMOS setup and saving and exiting CMOS should resolve your issues. Additional information about entering the BIOS setup can be found on document CH000192.

BIOS update recently performed

If you've recently ran a BIOS update on the computer the values stored in CMOS may have been reset. Enter CMOS setup and re-enter all the appropriate values. Additional information about entering the BIOS setup can be found on document CH000192.

If you're unable to enter the BIOS setup or after running a BIOS update your computer no longer keeps its values the incorrect BIOS update may have been installed for your computer or the version downloaded may be corrupt. We suggest trying to update the BIOS again and/or reverting back to an earlier version. Additional help and information with BIOS updates can be found on document CH000236.