BIOS & startup · medium

How to fixCMOS-CHECKSUM-ERROR

CMOS Checksum error

What this error means

CMOS-CHECKSUM-ERROR is a medium-severity hardware BIOS/UEFI problem. BIOS detected invalid data in CMOS. Settings have been lost. It sometimes comes down to power failure. Work through the steps below in order.

Before you begin

Save open work and back up important files. Note any recent driver or hardware changes. If Windows cannot start, use the startup guide first.

Work through these checks

0 of 3 complete
01Replace the CR2032 battery

Replace the CR2032 battery.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

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02Reset date/time

Reset date/time.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

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03Save the BIOS settings

Save the BIOS settings.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

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Possible causes

  • Low CMOS battery
  • Reset BIOS
  • Power failure