How to Replace the CMOS Battery

When your computer is turned off, a lithium battery maintains the current time-of-day clock and the values in CMOS RAM.

The battery should last about seven years. When the battery voltage drops below a certain level, the Setup program settings stored in CMOS RAM (for example, the date and time) might not be accurate. Replace the battery with an equivalent one.

Warning
Danger of explosion if the battery is incorrectly replaced. Replace only with the same or equivalent type recommended by the equipment manufacturer. Discard used batteries according to the battery manufacturer’s instructions.

To replace the battery, follow these steps:

1. Observe the precautions detailed in the ‘Safety and Regulatory Notices’ at the front of the Owner's Handbook.
   
   
2. Turn off and disconnect all peripheral devices connected to the computer. Then turn off the computer and remove the power cord.
   
   
3. Remove the computer cover. To get clear access to the battery, you may have to remove the system processor, or have an approved service engineer temporarily jack the motherboard out of the casing.

Caution
The motherboard must only be removed from the system case by an approved service engineer. The user should not attempt this procedure.

4. Locate the battery on the motherboard.
   
   
5. With a small non-metallic tool, gently pry the battery free from its socket. Note the orientation of the "+" and "-" on the battery.
   
   
6. Install the new battery in the socket, orienting the "+" and "-" correctly.
   
   
7. Replace the computer cover.