If your desktop PC is losing it’s date and time settings every time there’s a power cut, then the chances are that it’s internal battery is flat. During the system boot up, you are likely to encounter the CMOS checksum error which looks something like this,
The CMOS battery feeds a tiny amount of power to certain components of your computer which ensures that all of it’s settings, including date, time and other important settings are saved when it’s disconnected from the main power source.
If this battery goes then as soon as the computer is unplugged it will lose all of it’s settings.
Thankfully, it’s quite easy to change the battery yourself, and replacements are available in most computer hardware stores for a very small amount of money.
What battery do I need?
If your computer was built in the last 10 years or so then it will use a Lithium-Ion coin cell, similar to the ones used in watches and car central locking remotes.
The exact model number for the battery is: CR2032
They’re available from any computer store, as well as most superstores.
I managed to pick 2 batteries up from a local store for under $6.
How to change the battery.
Changing the battery will require about 5 minutes of your time, and maybe a couple of screwdrivers.
The procedure for doing it is like so:
- Disconnect all cables from your PC.
- Move it somewhere that you can work on it easily.
- Remove the side panel (refer to your PC’s service manual).
- Locate the dead cmos battery, it’ll look something like this
- Using a straight edge screwdriver, press on the clasp. The battery should then pop part way out of the holder.
- Remove the existing battery and you should see an empty socket like this,
- Take your new battery and place it in the slot, press down until it clicks into place.
- Replace your PC’s side panel.
- Reconnect all the cables and turn it on.
You’ll need to reset all your BIOS settings one last time, but now that the new battery is in place your PC should retain it’s settings when disconnected from the mains.