CMOS Checksum Error (resets settings on every boot)
Motherboard non-volatile memory loses stored configuration and date/time whenever AC wall power is removed.
Internal desktop parts run on harmless 12V DC voltage and cannot shock you. Simply unplug the wall power cable first, then touch the unpainted metal case frame to ground static electricity.
Common Symptoms & Tells
- Prompt: ' checksum error - Defaults loaded' on boot
- System clock resets to year 2018 or 2020 every shutdown
- Overclock and XMP profiles are forgotten every power cut
Interactive Fix Checklist
0 of 5 steps completedSafety power-off and discharge
Shut down the PC, turn off the power supply rocker switch (O), and unplug the AC power cord from the wall outlet. Press the front power button once while unplugged to discharge residual capacitor energy before touching any internal components.
Replace CR2032 3V coin cell battery
Standard motherboard CR2032 lithium batteries last 3-5 years. Replace with a fresh brand-name battery.
Check CMOS clear jumper position
Verify the CLR_CMOS jumper cap is not left in the 'Clear' position across pins 2-3 instead of normal pins 1-2.
Update to the latest stable BIOS revision
Corrupted EEPROM storage sectors can trigger checksum mismatches; flashing fresh firmware overwrites damaged sectors. CRITICAL SAFETY: Never turn off, reset, or unplug the PC while the update is flashing. A power interruption during EEPROM write will corrupt the firmware and brick the motherboard.
Save BIOS settings with F10 before exit
Ensure you explicitly save changes with F10 rather than exiting without saving.
Still having trouble with your PC?
Describe what is happening to your AI Technician. We will tailor the fix to your exact hardware setup.