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

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 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 or Reset Configuration Data.

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.

• How to replace the CMOS battery.

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 make sure the battery is charged before disconnecting the power connection.

If the CMOS values have become corrupted enter the correct values in CMOS setup and then save and exit CMOS setup to resolve your issues.

BIOS update recently performed

If a BIOS update has been run on the computer the values stored in CMOS may have been reset. EnterCMOS setup re-enter all values and then save and exit CMOS setup.

If you're unable to enter the CMOS 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 or reverting back to an earlier version.

CMOS checksum error

Most likely the battery on your system board is kaput. They are cheap, easy to find at most electronics retailers, and pretty simple to replace.

After opening the case of your system unit, look for something about the size and shape of a quarter mounted on the system board. Usually the battery sits under a tight clip and you can remove it by lifting the clip. Sometimes they snap into a socket and you have to push a little tab to release them.

After replacing the battery, start up your computer and press the appropriate key to enter the BIOS setup screen. (Usually it's the DELETE or INSERT key. Watch the screen for instructions or consult your manual.)

Set the system clock to the correct time, then save and exit. If your computer works normally now, you're all done. If it doesn't recognize one or more hard drives, go back into Setup and look for the hard drive "Auto config" or similar. Sorry if that's a little vague, but every BIOS is different, so it's impossible to give more detailed instructions. Poke around a bit, you'll find it!