How to Remove A CMOS Battery

By Randall Shatto

The CMOS battery protects your BIOS and CMOS settings by keeping a small amount of power supplied to the BIOS chips even when the PC is unplugged. If you have a power outage, or if your PC becomes unplugged, the battery will keep all of your BIOS settings and keep the correct time on your PC. If somebody sets a boot password on the BIOS, you can remove it by removing the CMOS battery and unplugging it from the wall. This will reset the information contained in the BIOS and RTC chips and remove the password.

Things You'll Need

  • Phillips head screwdriverTweezers

Step 1

Turn off the computer. Unplug all device cords from the back. Remove the screws on the right panel of the tower. Lay the computer facing up on the floor or a table.

Step 2

Locate the battery. The CMOS battery is similar to a watch battery except bigger. It is on the motherboard held on by thin metal tabs. Some computers have it flat against the board while others have it in an upright slot.

Step 3

Use your fingernails or a pair of tweezers to remove the CMOS battery. Lift the metal tab gently. It is a weak metal and can break easily. Do not lift the tab all the way or pull it off. Take the tweezers or fingernail and place it under the battery in the casing. Gently lift up and pull it out.

Step 4

Replace the panel and plug in the devices.

Tips & Warnings

  • The metal tabs holding the CMOS battery in are important. If the tabs break and you move the case, the battery will fall out.Insert a new battery by lifting the tabs and pushing it in.You do not need a CMOS battery to run your computer.Most CMOS batteries are interchangeable, as long as it is the right size for the casing.