Catherine from AZ writes:
How do you locate and change the (CMOS) clock battery? I have windows XP Dell Inspiron – 530S.
The clock battery (otherwise known as the CMOS battery) is a battery that is used to keep the system clock counting and the user settings saved in your motherboard’s circuitry. Over time, the battery can run out of energy and require replacing. These batteries are style CR2032 and are very easy to replace.
From Page 157-158 of Dell Service Manual  (Download relevant pages here ) the instructions for replacing the battery simply ask you to open the case and locate the battery (it is contained on the motherboard, the circuit board all the cables/CPU plugs in to). Remove the battery by pulling the battery release lever and put a new battery in its place.
Note: Make sure to unplug the power cable from your computer before poking around in there. You have been warned!
Replacing the battery can reset your saved motherboard settings (and date/time), so you’ll be asked to rerun the setup utility for your motherboard by pressing Del or F2 when the computer boots up. Consult your computer manufacturer for what settings need to be changed (if any) from the default settings and how to set the time/date in the CMOS setup. Once you are done, you will want to save and reboot and your computer should boot up normally with a new working clock battery.