What is CMOS-CHK-ERR?
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.
Common Causes
- Dead battery CR2032
- Short circuit on the motherboard
- Aborted BIOS update process
- Age of capacitors
Step-by-Step Fix Guide
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1
Replace the CMOS battery on the motherboard
Most reports of CMOS-CHK-ERR clear up after Replace the CMOS battery on the motherboard, so it's worth trying before anything more involved.
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2
Use the USB BIOS Flashback function (if the board has a button)
For cases that don't clear up right away, the remaining steps target less typical mobo instability problems.
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3
Check the rear I/O panel for a short
If earlier steps didn't help, "Check the rear I/O panel for a short" directly addresses short circuit on the motherboard.
Commands & Diagnostics
systeminfo | findstr /C:"BIOS Version"
Frequently Asked Questions
In most cases, dead battery CR2032 is behind CMOS-CHK-ERR. Short circuit on the motherboard, aborted BIOS update process and age of capacitors can trigger it too.
The fastest fix is "Replace the CMOS battery on the motherboard". Only move on to the later steps if CMOS-CHK-ERR keeps coming back.
Treat CMOS-CHK-ERR as urgent — it's flagged critical severity, meaning repeated occurrences risk data loss or hardware damage.
Usually. CMOS-CHK-ERR is fixable with the steps above; a full Windows reinstall is rarely necessary unless everything else has failed.
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