Resetting your CMOS restores your motherboard's BIOS or UEFI settings back to their factory defaults.

This can be useful if your PC becomes unstable, fails to boot, displays a black screen after changing BIOS settings, or if an optimization was applied that your hardware does not support.

Important: Resetting your CMOS does not delete Windows, games, personal files, or applications. It only resets BIOS or UEFI settings.

Before You Begin

Before resetting your CMOS:

  • Shut down your PC completely.

  • Turn off the power supply using the switch on the back of the PC.

  • Unplug the power cable from the wall or power supply.

  • Disconnect unnecessary USB devices.

  • Press and hold the PC's power button for around 10 seconds to discharge any remaining power.

If you use custom BIOS settings such as XMP/EXPO, Resizable BAR, fan curves, virtualization, Secure Boot settings, or custom boot settings, you may need to enable them again afterward.

Method 1: Use the Clear CMOS Button

Some motherboards include a dedicated Clear CMOS button.

The button may be located:

  • On the rear I/O panel of the motherboard

  • Directly on the motherboard

  • Near the BIOS Flashback button

With the PC powered off and unplugged:

  1. Locate the Clear CMOS, CLR CMOS, or similarly labeled button.

  2. Press and hold the button for approximately 5 to 10 seconds.

  3. Release the button.

  4. Reconnect the power cable.

  5. Turn the power supply back on.

  6. Start your PC.

Your BIOS settings should now be reset.

Method 2: Use the Clear CMOS Pins

Most desktop motherboards contain two pins specifically designed for clearing CMOS.

These may be labeled:

  • CLR_CMOS

  • CLRTC

  • JBAT1

  • CMOS

  • CLEAR

The exact name and location depend on your motherboard.

  1. Shut down and unplug the PC.

  2. Locate the Clear CMOS pins on the motherboard.

  3. Touch both pins simultaneously with the metal tip of a screwdriver for approximately 5 to 10 seconds.

  4. Remove the screwdriver.

  5. Reconnect the PC and turn it on.

Do not touch random motherboard pins. If you cannot identify the correct Clear CMOS pins, check your motherboard's manual before proceeding.

Method 3: Remove the CMOS Battery

Most desktop motherboards use a small round CR2032 battery to retain BIOS settings.

To reset the CMOS using the battery:

  1. Shut down the PC.

  2. Turn off the power supply.

  3. Disconnect the power cable.

  4. Press the power button for approximately 10 seconds.

  5. Locate the round silver CMOS battery on the motherboard.

  6. Carefully release the retaining clip holding the battery.

  7. Remove the battery.

  8. Wait approximately 5 minutes.

  9. Reinstall the battery with the positive + side facing upward.

  10. Reconnect power and start the PC.

On some systems, waiting longer may be necessary before the CMOS fully clears.

What Happens After a CMOS Reset?

The first startup after resetting CMOS may take longer than normal.

This is especially common on newer systems using DDR5 memory because the motherboard may need to perform memory training.

You may also see a message such as:

  • BIOS settings have been reset

  • CMOS checksum error

  • Press F1 to enter setup

  • Defaults have been loaded

This is normally expected.

Enter your BIOS and verify important settings before continuing into Windows.

Settings You May Need to Re-Enable

Depending on your system, resetting CMOS may disable or change:

  • XMP or EXPO memory profiles

  • Resizable BAR

  • Secure Boot

  • TPM/fTPM

  • CPU virtualization

  • Fan curves

  • Boot priority

  • RAID settings

  • Custom CPU settings

  • Custom RAM settings

Only change settings that you understand or that were previously configured on your system.

If Your PC Still Does Not Boot

If the system still does not boot after resetting CMOS:

  • Give the system several minutes on its first startup.

  • Confirm that your RAM and GPU are properly seated.

  • Confirm your monitor is connected to the correct graphics output.

  • Try booting with one RAM stick.

  • Check your motherboard's debug LEDs or error codes.

  • Consult your motherboard manufacturer's documentation.

If your motherboard supports BIOS Flashback, that may also be useful if the BIOS itself has become corrupted.

Laptop Users

We generally do not recommend opening a laptop solely to reset CMOS unless you are comfortable servicing the device.

Laptop CMOS reset procedures vary significantly between manufacturers and models. Some laptops may use an internal battery, service connector, keyboard shortcut, or manufacturer-specific recovery procedure.

Refer to your laptop manufacturer's documentation for the correct reset procedure.

Need More Help?

If you are unable to recover your PC after resetting CMOS, contact EXM Support and include:

  • Your motherboard or laptop model

  • CPU

  • RAM

  • GPU

  • What happened before the issue started

  • Any motherboard debug LEDs or error codes

  • Photos of any error messages, if available

Our support team can help determine the next troubleshooting steps.