[b]How to Tell if a CMOS Battery is Low[/b] [img]http://i.ehow.com/images/GlobalPhoto/Articles/2217933/CMOS-main_Thumb.jpg[/img] Is your computer's clock falling behind or continually incorrect even though you might have reset the time? Read these tips to learn how to tell if a CMOS battery is low. Things You’ll Need: Computer Step 1: The CMOS or "Complementary Oxide Metal Semiconductor" is the storage unit for the BIOS (Basic Input Output System) of your computer. This keeps you from losing your computer's motherboard information each time you shut down. Step 2: When the CMOS battery does get low, it will not be a crisis initially. You will have some time to open your computer and find out what replacement battery you will need. Step 3: With some computer models, you will receive an error message on your screen initially at startup. This message varies by manufacturer. You may also see a prompt at start up that states "Press F1 for setup or F2 to load default values." Know that this could vary by computer brand. Step 4: Sometimes the computer will not show signs of failure at each boot up. It may be more random at first. Or, your computer may get to a certain point in the start up process and then freeze. And, rebooting does not seem to help this problem. Step 5: Eventually, when the battery is drained entirely, it will not be able to save any of your settings and then the CMOS will need to be replaced.