What is CMOS and How to Reset?

If you’ve ever opened up a computer case or seen the inside of a motherboard, you may have noticed a small battery and a small chip labeled “CMOS.” But what exactly is CMOS, and why is it important? In this article, we will answer these questions and guide you through the process of resetting your CMOS.

What is CMOS?

CMOS stands for Complementary Metal-Oxide-Semiconductor, and it refers to a type of technology used in the creation of electronic components. In the context of a computer, the CMOS refers to a small amount of memory that is used to store the computer’s basic settings, such as the date and time, boot order, and hardware configuration.

The CMOS is powered by a small battery on the motherboard, which keeps the CMOS memory powered even when the computer is turned off. This ensures that the computer’s settings are not lost every time the power is turned off.

Why Reset CMOS?

Sometimes, the settings stored in the CMOS can become corrupted or outdated, which can cause problems with the computer’s boot process or performance. In some cases, resetting the CMOS can fix these issues.

Additionally, if you’ve made changes to your computer’s hardware configuration, such as installing a new graphics card or upgrading the RAM, you may need to reset the CMOS to ensure that the computer recognizes the new hardware.

How to Reset CMOS

Resetting the CMOS is a relatively simple process, but it does require some knowledge of the computer’s hardware. Before you begin, you’ll need to gather a few tools:

  • Step 1: Shut Down Your Computer. Before you begin, make sure that your computer is turned off and unplugged from the power source.
  • Step 2: Locate the CMOS Battery and Jumper. The CMOS battery is usually located near the center of the motherboard, and it looks like a small silver disc. It may be held in place by a clip or a small metal bracket. Next to the CMOS battery, you should see a set of three pins labeled “JP1” or “CLRTC.” This is the jumper that you will use to reset the CMOS.
  • Step 3: Remove the CMOS Battery. Using your Phillips-head screwdriver, gently pry the clip or bracket holding the CMOS battery in place. Once the battery is free, carefully remove it from its socket.
  • Step 4: Short the Jumper. Using your jumper cap (or a small piece of metal wire), carefully connect the two pins on either side of the center pin on the CMOS jumper. Hold the jumper in place for about 10 seconds.
  • Step 5: Reinstall the Battery. Remove the jumper cap and carefully reinstall the CMOS battery into its socket. Make sure that it is securely in place and that the clip or bracket is holding it firmly.
  • Step 6: Power On Your Computer. Finally, plug your computer back in and turn it on. If everything went smoothly, you should see a message on the screen indicating that the CMOS has been reset.


Resetting the CMOS can be a helpful tool in fixing certain computer issues, but it’s important to proceed with caution. If you’re unsure about any part of the process, it’s best to consult with a professional or experienced friend.

As always, be sure to back up any important data before making changes to your computer’s hardware or settings. With the right tools and knowledge, you can keep your computer running smoothly for years to come.

Leave a Comment