Motherboard · critical

How to fixCMOS-CHK-ERR

Corrupt CMOS checksum

What this error means

Corrupt CMOS checksum (CMOS-CHK-ERR) is a critical-severity fault affecting the motherboard. The BIOS has lost its settings due to a dead coin-cell battery on the board. Reports of Corrupt CMOS checksum usually describe a sudden crash, brief unresponsiveness, or a stop-code screen appearing out of nowhere. Common triggers are short circuit on the motherboard and age of capacitors. Use the steps below to track down and fix the cause.

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 CMOS battery on the motherboard

Replace the CMOS battery on the motherboard.

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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02Use the USB BIOS Flashback function (if the board has a button)

Use the USB BIOS Flashback function (if the board has a button).

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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03Check the rear I/O panel for a short

Check the rear I/O panel for a short.

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

  • Dead battery CR2032
  • Short circuit on the motherboard
  • Aborted BIOS update process
  • Age of capacitors