Getting CMOS Checksum is invalid

[MTBMark]

Hi,

i recently updated my BIOS and now when turning on the PC from being switched off at the wall, the PC gos straight into a boot up, i don't press the ON button - it just tries to start a couple of times, unsuccessfully, then the screen displays the message:

The CMOS Chechsum is invalid. The CMOS WILL RESET TO THE DEFAULT CONFIGURATION, AND THE COMPUTER WILL REBOOT

CMOS Reset (502)

the PC will then boot into windows 10 fine.

this doesn't happen if i turn off the PC but leave the power connected.

I have run the diagnostics which show the BIOS is up to date, and no errors showing.

Any ideas please?

many thanks

[zoey7886 · Accepted solution]

@MTBMark, Welcome to the HP Support Community!  

Thanks for reaching out about your query regarding CMOS Checksum Error: Troubleshooting Guide! 

We're thrilled to have the opportunity to assist you and provide a solution.  

When encountering a "CMOS Checksum is invalid" error, there are a few steps that can be taken to resolve this issue. This error commonly arises after BIOS updates or due to CMOS battery issues. Follow the steps below to troubleshoot and fix the problem:

Steps to Resolve CMOS Checksum Error:

Verify the CMOS Battery:

• The CMOS battery may need to be replaced. It is recommended to replace it with a new battery to ensure it is not causing the issue.
• How to Replace CMOS Battery:
  1. Turn off the computer and any external devices.
  2. Disconnect the power cord from the power outlet.
  3. Remove the access panel from the computer.
  4. Locate and remove the CMOS battery from the motherboard.
  5. Install a new CMOS battery in the same position.
  6. Replace the access panel and reconnect the external equipment.
  7. Plug in the computer and turn it on.

Reset CMOS Values:

• Resetting the CMOS values to default can help resolve the error.
• Procedure to Reset CMOS Settings:
  1. Turn off the computer and disconnect the power cord.
  2. Press the power button to drain any residual power.
  3. Remove the access panel and locate the CMOS jumper on the motherboard.
  4. Remove the jumper from pins 1 and 2, and then place it on either pin 1 or 2 but not both.
  5. Replace the access panel.
  6. Reconnect the external equipment and power on the computer.
  7. Check if the error is resolved.  

Hope this helps! 

Take care, and have an amazing day!  

Did we resolve the issue? If yes, Please consider marking this post as "Accepted Solution" and click "Yes" to give us a helpful vote - your feedback keeps us going!  

Regards, 

[MTBMark]

Hi Zoey7886,

Thank you for taking the time to reply. 

I carried out the steps detailed and now the PC boots up without the CMOS error. So that's great!

Much appreciated, 

MTBMark

[zoey7886]

@MTBMark, A huge thank you for marking this post as the 'Accepted Solution'! We're thrilled that we could help resolve your issue. 

If you have any more questions or need further assistance, please don't hesitate to ask. We're here to help! 

Thanks again for your confirmation, and we wish you an amazing day ahead! 

Regards,