Changing CMOS Battery

Some times your clock starts computer running slowly, or when you boot (start) your computer it has a problem finding your hardware, that the sign of a battery failing. You must to change your battery.
To change the battery you need the following tools
1) a X-point screwdriver to open your computer case.
2) an anti-static strap(optional)
3) a new battery (seems logical)

Unplug all the cables from the back of the computer. Move the computer somewhere where you can work on it with ease. Remove the cover by locating the screws around the outer edge (back) of the computer. Then locate your battery at you motherboard, you will see a round silver thing that looks about the size of a 10p piece (quarter). This is the battery itself, carefully lift the retaining clip and slide the battery out. Insert the new battery by lifting the clip and sliding the battery in. Reinstall your case and plug all the cables back.

Then turn on your computer and go to Bios Setup by press del or F2 or ESC (depend on BIOS) when it booting. You will now be presented with a blue screen with a lot of options on it, the one we want is load optimised/default settings. Press the F10 key and type y the computer should now reboot. If every thing went well then your computer will now be up and running.