How to Fix CMOS Battery Failure

By Andrew Bell

Is your computer telling you that the date and time needs to be set every time you boot your system? Other common errors indicating that your battery is dead are "CMOS checksum error" or "CMOS Battery Failure." If you are experiencing any of these symptoms or errors, follow the simple steps below to fix the CMOS battery failure.

Things You'll Need

  • CMOS battery
  • Philips and flat-head screwdrivers

Step 1

Unplug all of the cables from the back of your computer and turn it on its side so that the case panel faces toward you.

Step 2

Remove the Philips screws or thumb screws to release the case access panel.

Step 3

Remove the access panel. Be careful if you suspect that there is a fan attached to the panel as it needs to be unplugged from the power supply.

Step 4

Locate the CMOS battery, typically a round, silver, 1/2-inch disk located on the motherboard.

Step 5

Remove the CMOS battery by placing a small flat-head screwdriver under the battery and popping it out of its slot.

Step 6

Insert the new battery into the slot and gently press into place. Reassemble your computer and reconnect all of the appropriate cables.

References & Resources