How to change a computer's CMOS battery
From ArticleWorld
When you turn your computer off, only some small parts of its settings need to be saved permanently so that, when powering it on again, it will start correctly. These are the BIOS settings, which are essential for starting up your computer. Without them, the computer will not know how to use the boot disks and the peripherals needed to boot the computer.
These settings are stored in the CMOS chip, which is always powered by a battery. Still, this battery sometimes fails, although it is thought to last for years. It is especially common with older computers.
Your CMOS battery may need replacement if you notice any of the followings:
- Strange errors when booting, referring to the fact that the BIOS settings have been reset to default.
- Problems with your computer's date, which often seems to reset to a strange default date or fall behind with minutes in only a matter of days.
- Inconsistency when booting, require the computer to be powered on and off several times before booting correctly.
If you notice any of the following and cannot find any other solution, this may be a good thing to try.
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Steps
- First of all, make a list of your computer's BIOS settings. Boot up your computer and go to the BIOS settings screen (usually by pressing delete just after powering it on; refer to your motherboard's documentation for details). Go through all the screens and write everything down.
- Turn off the computer and unplug it, then remove its cover.
- Take a look on the motherboard, comparing what you see with the diagram you should have in your motherboard's manual. Alkaline and lithium batteries are held in small containers on the motherboard and can be easily replaced. Those that are built-in are soldered, but they have spare connectors for extra batteries. Look at the connector and retain its type if it is labeled, or at least how it looks.
- Purchase a similar battery. Remove the old one or attach the new one to a spare connector, in exactly the same polarity. Plug the power cord and start the computer.
- If needed, remake any settings that may have been lost by going tot the BIOS settings screen again.