How To Replace The CMOS Battery on a Motherboard

How To Replace The CMOS Battery on a Motherboard
Page content

Why Change The Battery?

Every computer motherboard has one battery. It is used for two purposes:

  1. Retaining the date and time of the PC’s clock.
  2. Retaining the computer hardware configurations.

If you see any of the messages below when you turn on your PC, it is now time to replace the motherboard battery with a new one:


Another indicator of a low motherboard battery is the computer clock that shows wrong time when you turn on your computer after once turning off.

Write Down CMOS Settings

CMOS values are used to initialize the computer. If these are lost, the computer time will be reset, system boot sequence and other hardware configurations will be lost.

So, it is necessary to write down all the CMOS values before removing the battery. Turn on or restart the computer and press F1, F2 or Del button (button vary from computer to computer) to enter the setup program. The most important settings you need are system boot sequence, drives configuration and shared memory size. You will need to enter them back in the CMOS after replacing the battery, so write them down on a piece of paper.

Note: Don’t worry if you forget recording CMOS values before removing the battery, your computer will still work fine, just the settings will be reset to factory default and you may need to re-configure them to suit your and hardware requirement.

Locate The Battery

Open your computer case and locate the motherboard battery. Most computers use a 3V coin cell lithium battery as shown in the right image. The battery is usually located at one of the extreme

corners of the motherboard. If you’re unable to find the battery, you’ll need to read the motherboard documentation that came with it or contact motherboard’s manufacturer for assistance in finding it.

Replace The Battery

Caution: Before you open your computer case, make sure the computer is off and the power cable unplugged to avoid possible electric shock while in the computer.

Removing a motherboard battery is very easy. Simply use your two fingers to gently grab the battery from its edges then pull it out from the socket holding it. If there is a tiny clip holding down the battery, you will need to pull that clip up before pulling the battery out of the container.

Once you’ve bought a new motherboard battery, remove the old battery as instructed earlier and put the new one in the same configuration ( + or – settings).

Note: Unfortunately, not every motherboard use coin cell batteries. If you are not using this battery and aren’t able to remove it, consult your motherboard manufacturer for help in removing the battery.

Enter Back CMOS Values

Once you have successfully replaced the battery, turn on your computer and press the F1, F2 or Delete key (vary from computer to computer) to enter setup. Enter all the CMOS values and make sure you save the new settings before exiting the setup. Some motherboard setups allow you to save the settings and exit together by just pressing one button such as F10.

This is it! Replacing a motherboard battery was easy. Your new motherboard battery will last for several years, though some last much longer depending on the amount of use. If after that time the system time resets again every time you turn off and turn back on your computer, you will need to change the battery again.

Motherboard not Recognizing Hard Drive?

Basic Motherboard Fault Checking

Image Source