Gently pop the battery out using a small flathead screwdriver.
Locate a 2-pin or 3-pin jumper labeled , CLR_CMOS , JBAT1 , or RTCRST .
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When your PC cannot boot into Windows, you must run these utilities from a bootable USB drive or a pre-boot environment like Hiren’s BootCD. Below are the most reliable classic utilities available for download. 1. CMOS De-Animator
: Supports almost all x86 and x86_64 motherboards and works with major BIOS brands such as Award, AMI, Phoenix, and Compaq. Gently pop the battery out using a small
Insert the prepared USB drive into the locked computer. Restart the system and enter the BIOS/UEFI setup (usually by pressing F2 , F10 , Del , or Esc immediately after powering on). Navigate to the Boot section and set the USB drive as the first boot device. Save changes (usually F10 ) and exit.
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It modifies the values in the CMOS registers to corruption states, forcing the motherboard to automatically reset itself to factory defaults upon the next reboot.
Restart your computer. During the reboot, tap Del or F2 to enter your BIOS. You should see a message stating "CMOS Checksum Error - Defaults Loaded," confirming the reset was successful. What to Do If Software Fails: Physical CMOS Clearing
These update the BIOS firmware , not clear saved settings. They are dangerous for average users because a failed flash can brick your motherboard.