What is CPU-FAN-ERROR?
CPU-FAN-ERROR shows up as a high-severity Windows operating system fault. The motherboard BIOS cannot detect a CPU fan signal during POST. System may refuse to boot to protect the CPU. The usual suspects are fan not connected to CPU_FAN header and faulty fan motor. Use the steps below to track down and fix the cause.
Common Causes
- Fan not connected to CPU_FAN header
- Fan speed too low for BIOS threshold
- Faulty fan motor
Step-by-Step Fix Guide
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1
Check connection to CPU_FAN header
"Check connection to CPU_FAN header" targets fan not connected to CPU_FAN header, one of the documented causes of CPU-FAN-ERROR.
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2
Lower 'CPU Fan Speed Lower Limit' in BIOS
"Lower 'CPU Fan Speed Lower Limit' in BIOS" is worth trying when fan speed too low for BIOS threshold turns out to be the culprit.
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3
Replace CPU cooler
Still seeing CPU-FAN-ERROR after that? "Replace CPU cooler" is the next thing to check.
Commands & Diagnostics
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Frequently Asked Questions
Fan not connected to CPU_FAN header accounts for the majority of CPU-FAN-ERROR reports; fan speed too low for BIOS threshold and faulty fan motor come up less often but are documented.
Most CPU-FAN-ERROR reports resolve after "Check connection to CPU_FAN header". The rest of the guide above is there for the cases that don't.
CPU-FAN-ERROR is a high-severity error. It won't damage your PC instantly, but repeated occurrences usually point to a deeper problem worth addressing soon.
You shouldn't need to. Work through the guide above first — a reinstall is only worth considering if none of those steps help.
Sometimes. Microsoft regularly releases patches that fix known BSOD triggers including CPU-FAN-ERROR. Make sure Windows is fully up to date via Settings → Windows Update before attempting more advanced fixes.
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