CMOS checksum error

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 settings and then exit CMOS setup.

If everything appears to be correct, you can try resetting the CMOS to the default values. After the CMOS values are reset, save changes and exit the BIOS to reboot the system.

CMOS batteryTip: If this issue continues to occur after you turn off your computer off the CMOS battery may be failing or already bad. Before considering replacing the CMOS battery try leaving your computer on for several days. Sometimes leaving the computer can re-charge the battery.

Computer improperly turned off

If the computer lost power while it was still running it may have corrupted the CMOS. Make sure 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. Enter CMOS setup re-enter all values and then save and exit CMOS setup.

If you are unable to enter the CMOS setup, or the computer no longer keeps its BIOS values, the BIOS update may be corrupt. In this case, we recommend updating the BIOS again or reverting to an earlier version.

Additional information

  • See the BIOS and CMOS definition for further information about each of these terms and related links.