MICROCODE_REVISION_MISMATCH
What is this error?
The CPU microcode loaded by the BIOS doesn't match what Windows expects. This indicates a BIOS/CPU firmware issue.
Common causes
- outdated BIOS missing microcode update
- BIOS downgrade removed microcode
- CPU not fully supported by current BIOS
- Intel/AMD security patch missing
How to fix it
- Update BIOS to the latest version immediately
- This is a firmware issue that only BIOS updates can fix
Too many steps? Crashless can diagnose this automatically — checks your drivers, temps, VRAM, and 400+ known error patterns.
Get free AI diagnosis Detailed analysis
Bug check 0x0000017E (MICROCODE_REVISION_MISMATCH) means the CPU microcode in your BIOS is outdated or incorrect. Microcode is low-level CPU firmware loaded during boot — if it's wrong, Windows can't trust the CPU to operate correctly.
This is critical for Intel 13th/14th gen CPUs where microcode updates prevent hardware degradation.
How to fix it:
- UPDATE YOUR BIOS IMMEDIATELY — this is the only real fix. Download the latest BIOS from your motherboard manufacturer's website
- Flash the BIOS following the manufacturer's instructions (usually through BIOS itself or a USB flash utility)
- After updating, reset BIOS to default settings
- For Intel 13th/14th gen: ensure the BIOS includes microcode 0x129 or later — this prevents CPU vCore degradation
- If you previously downgraded your BIOS, upgrade back to the latest version
- Do NOT ignore this BSOD — running with mismatched microcode can cause data corruption and hardware damage
- If BIOS update doesn't fix it, contact the motherboard manufacturer for support
When to seek help
If this error keeps happening after trying the fixes above, it may point to a deeper hardware or system issue. Consider professional help if:
- The crash occurs across multiple games or applications
- You see the same error after a clean Windows install
- Your PC is less than a year old (could be a warranty issue)
- You smell burning or hear unusual sounds from your PC
Or let Crashless do the deep analysis for you -- our AI checks drivers, temps, event logs, and 400+ known patterns automatically.
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