If the clock on your computer keeps resetting itself back to the 1980s it could be a sign that the motherboard battery needs replacing.

You might not have realised that the motherboard has a battery, but it uses it to power the clock when the computer is not plugged in. Annoyingly it is not rechargeable so it will need replacing after a few years.

This battery also keeps some of the computer settings safe. As these need less power than the clock, they may last for some time after the clock stops working. They won’t last forever, so replace the battery as soon as this happens.

As well as the clock losing time, you may also find that there are problems with the anti-virus software, as it uses the date to check for the latest updates. Sometimes the computer won’t boot unless you press a key when you turn it on, and there is a message along the lines of 'RTC battery is discharged'. This stands for real-time clock.

Most batteries are ordinary button-type batteries; the boards we looked at when researching this video were CR2032 that you can buy from shops on the high street. It’s a good idea to check in the case first to avoid wasting any money.

Here we have a case with the side removed and you can just see the battery down here. They are normally flat on the board, but we have seen a few mounted vertically.

So you can better see the process, we are replacing the battery on a motherboard mounted on a special tray.

Always disconnect the motherboard from the power supply before making this change. If there is still power going to the motherboard it could be damaged.

In fact, because there is a certain amount of power left in the system even when the power is not connected, press the power button to drain it completely. You may even see the fans start to turn, that shows how much power is there. There is often a small LED light on the motherboard that is lit when there is power, this should be off too.

To remove the battery, press against the catch with a fingernail and the battery should pop out; the contact below works like a spring.

Carefully remove the old battery, there will probably be a catch on the side of the fitting and it should pop out. Dispose of the battery properly, it shouldn’t be just thrown into the bin, most councils will have battery recycling facilities.

Insert the battery with the text uppermost and press it into place. It’s best to insert it from the side opposite the catch. Once the battery is in place replace the power connector and the side of the case. The computer is now working again though you may need to set the time one last time.