ACPI_BIOS_ERROR
What is this error?
The system BIOS is not fully ACPI compliant. The BIOS provides incorrect or incompatible power management information to Windows.
Common causes
- outdated BIOS
- BIOS misconfiguration
- hardware not ACPI compliant
- BIOS bug with Windows version
- incompatible CSM/UEFI settings
How to fix it
- Update BIOS to latest version
- reset BIOS to defaults
- disable CSM
- check ACPI settings
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 0x000000A5 (ACPI_BIOS_ERROR) means your motherboard's BIOS provides incorrect ACPI (Advanced Configuration and Power Interface) data to Windows. This is almost always a BIOS issue.
Common after building a new PC with an older BIOS version, or after changing BIOS settings.
How to fix it:
- Update BIOS to the latest version from your motherboard manufacturer's website — this is the #1 fix. ACPI tables are improved with each BIOS update
- Reset BIOS to default settings: enter BIOS, find 'Load Optimized Defaults' or 'Reset to Default', save and exit
- Disable CSM (Compatibility Support Module) in BIOS — ACPI works better in pure UEFI mode
- Make sure Secure Boot is enabled after disabling CSM
- If the BSOD started after overclocking, revert all overclock settings — some overclock profiles modify ACPI tables
- Check if your CPU is supported by the current BIOS version — some motherboards need a BIOS update for newer CPUs
- If using a very new CPU on an older motherboard, you may need a BIOS update before Windows can manage power properly
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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