Steps to Solve BIOS or CMOS ‘Checksum’ Error in Windows 10, Windows 8.1, Windows 8, Windows 7

repair CMOS checksum error

CMOS checksum error is one of the common PC/Laptop errors, which occurs when user turn on their system. If you are getting this CMOS error message and unable to boot your PC/Laptop then don’t worry as you can easily troubleshoot CMOS checksum errorBefore applying any solution to repair CMOS checksum error, first of all you should know about CMOS, causes of CMOS checksum error and hidden facts about this system error.


Also read: Step by Step Guide to Fix UNEXPECTED KERNEL MODE TRAP in Windows 10


Complementary Metal-Oxide Semiconductor in short CMOS is a battery powered semiconductor chip on the motherboard, which stores all the information related to the BIOS.

The checksum error is linked to the BIOS (Basic Input/Output System), it is the first running program when user power on the computer. BIOS is responsible to initialize and test the hardware, such as the CPU, memory, keyboard, mouse, etc.

This type of error message appears when CMOS battery gets exhausted or used up, if the BIOS values get damaged then it makes CMOS unable to retain data, and hence you’ll get the checksum error message.

This error message appears with a black screen window and some information about the error:

“Diskette drive 0 seek failure

CMOS checksum error – Defaults loaded

Press F1 to continue, F2 to enter SETUP”

Some Common Causes of CMOS Error

Improper Shutdown of System

This is one of the common causes of getting CMOS error; improper system shutdown can corrupt the BIOS values. Sudden power failure while using a computer (in case you don’t have UPS) may also affect the CMOS and lead to this error message. So it is recommended to connect your computer with UPS in order to deal with an unexpected power cut. Shutdown your computer or laptop after closing the entire running apps.

Note: If you are a Laptop user then make sure that the battery is fully charged before disconnecting the power connection.


Also Read: Complete Steps to Fix ACPI_BIOS_ERROR in Windows 10

After Updating BIOS

Sometimes when user updates system BIOS then values stored in CMOS may have been reset.

So, it is recommended to reset the CMOS and setup re-enter all values. After doing this save and exit from CMOS setup.


How to Troubleshoot CMOS Checksum Error on Windows System?

In order to overcome from CMOS Checksum Error on the windows system, you must apply below-given troubleshooting methods.


Method 1: Change the old CMOS Battery to Fix the Checksum Error

Exhausted CMOS battery is one of the common cause of checksum error generally, the battery of model number CR2032 3V become faulty very soon. So either contact any technician or purchase such battery from computer stores to replace your old one.

Note: If you are using Computer more than 5 years then it is recommended to replace the CMOS battery.

Replace OLD or NOT working CMOS battery:

  1. Buy a new CMOS battery.
  2. Shut down the computer and disconnect all the power supply for the CPU.
  3. Open the computer case and find the old battery on the motherboard.
  4. Carefully remove the old CMOS battery.
  5. Attach the new battery into the battery socket and double sure that the battery is firmly placed like the old one.

NOTE: If you are new to the computer or unable to replace CMOS battery yourself then it is recommended to contract computer technicians for help.


Method 2: Try to Reset the BIOS and Solve the “CMOS Checksum Error – Defaults Loaded” Problem

If you are still getting CMOS checksum error message while the startup of your PC or laptop then you should try after resetting the BIOS values. Simply follow the below-given steps:

  1. Start your computer to the black screen with the checksum error.
  2. After getting this error message “Press F1 to continue, F2 to enter SETUP”, press the F2key to enter the BIOS settings.


Note: To open BIOS setting you may need to press other keys (like the Del key). This is based on your BIOS.


  1. See the keys usage information on the screen and select the Load Defaults.
  2. If the system show “Load BIOS Defaults(Y/N)?”, then press the Y key to confirm.
  3. After doing this exit from the BIOS setting and turn off the computer. Again boot your PC to see if the error still persists or not.
  4. If the problem is still unfixed then again enter the BIOS setting.
  5. Choose the Standard CMOS Features.
  6. Check the Date and Time. If they are incorrect then modify the values and save the changes.
  7. Also, check the SATA or Drive. In case your system has no diskette drive on the computer, you can choose Disable/None/Not Detected to stop the diskette drive scanning.
  8. Save the changes and exit from the BIOS.

After all, turn on your Windows desktop and you will see that the error is gone.


Note: Different BIOS has different interfaces and option description. So it is recommended to double confirm before taking any action.

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