How To Fix: CMOS checksum error - defaults loaded

symptoms

When starting your PC, the following error message is displayed:

CMOS wrong      
CMOS MEMORY size WRONG       
CMOS Checksum Bad      
CMOS checksum error defaults loaded      
Warning! CPU has been changed please re-enter cpu settings in the cmos setup 
and remember to save before quit! 

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You are prompted to:

Press F1 to resume    
Press F2 to load default values and continue

This is due to the fact that the CMOS, which contains data related to the BIOS, has been reinitialized and that your PC has been reset to factory settings.

Solutions:

• Reinitializing the BIOS
  • Before making any costly maintenance try: reinitialized the BIOS.
• Change BIOS battery
  • If the problem persists this may be due to the fact that the battery powering the CMOS (when the computer is shut down it allows the CMOS to store information), is depleted.
  • The CMOS battery is a small pin found on the motherboard; you can refer to the manual provided with your motherboard to change it or have the nearby computer technician change it for you if you don't want to risk any damage.

  Replacing the CMOS battery

  The CMOS battery is thin round button-like object. It can sometimes be hidden by extension cards or connectors. On older PCs it may have a cylindrical shape. The most widely used battery model is the CR2032:
• Where :
  • CR- lithium battery
  • 20 - 20mm diameter
  • 32- Thickness 32* 0.1 mm
• This type of battery is easily found and fairly cheap to purchase

How to locate it:

• Turn off your PC
• Remove the power cable attached to your system unit and remove the casing.
• Discharge your system unit from static electricity by touching it with a metallic object.

Removing the discharged battery

First of all, be sure that your System unit is laid down horizontally. The positive pole of the battery should be visible. Remove the battery, but avoid forcing it and any contact with other parts of your motherboard (refer to the manual provide with your motherboard). Go to your local retailer any buy a battery of the same model or something equivalent.

Installing the new battery

Be sure that the battery is placed correctly (firmly) in the slot allocated

Verify the BIOS data and resetting the clock

Once the operation complete, it is important to configure the BIOS settings:

• Start your PC.
• Enter the BIOS.
• Modify the date.
• Check the parameters are the same as the ones noted in step 1
  • Perform any modifications required if not
• Save and quit BIOS.