Purpose

A CMOS reset restores BIOS/UEFI settings to default values and can help resolve startup issues, hardware detection problems, BIOS configuration errors, and system instability.

This procedure performs a power discharge reset, which is the recommended first step for most desktop and laptop troubleshooting. A full CMOS clear may require manufacturer-specific procedures depending on the device model.

Desktop Computer CMOS Reset (Power Drain Method)

Before You Begin

  • Save any open work.

  • Shut down the computer completely.

  • Disconnect any unnecessary external devices.

  • Obtain approval before performing hardware troubleshooting if required by your organization.

Procedure

  1. Shut down the desktop computer completely.

  2. Disconnect the power cable from the back of the computer.

  3. Turn off the power supply switch on the back of the computer (if available).

  4. Disconnect any additional power sources:

    • UPS devices

    • Power strips

    • External adapters

  5. Press and hold the computer's power button for 30 seconds.

    • This drains residual electrical charge from the system.

  6. Reconnect the power cable.

  7. Turn the power supply switch back on (if applicable).

  8. Power on the computer.

  9. Verify whether the issue has been resolved.

After Resetting

If the computer starts successfully:

  • Enter BIOS/UEFI setup if required.

  • Verify system date and time.

  • Confirm boot order.

  • Verify hardware devices are detected correctly.

Laptop Computer CMOS Reset (Power Drain Method)

Before You Begin

  • Save all work.

  • Shut down the laptop completely.

  • Disconnect the AC power adapter.

  • Remove any connected devices:

    • USB devices

    • External monitors

    • Docking stations

    • Peripherals

Procedure

  1. Shut down the laptop completely.

  2. Disconnect the AC adapter.

  3. If the laptop has a removable battery:

    • Remove the battery from the laptop.

  4. Press and hold the laptop power button for 30–60 seconds.

    • This discharges remaining power from the system.

  5. Reconnect the battery (if removed).

  6. Reconnect the AC adapter.

  7. Power on the laptop.

  8. Verify whether the issue has been resolved.

Internal Battery Laptops

Many modern laptops do not have a removable battery. For these systems:

  1. Shut down the laptop.

  2. Disconnect the AC adapter.

  3. Disconnect all external devices.

  4. Press and hold the power button for 30–60 seconds.

  5. Reconnect the AC adapter.

  6. Power on the laptop.

  7. Verify system operation.

Expected Results

After completing the reset:

  • BIOS/UEFI settings may return to default values.

  • System date and time may need to be corrected.

  • Boot order settings may need to be restored.

  • Hardware detection issues may be resolved.

  • Power-related startup issues may be corrected.