Cmos error 502

[RogerM1953]

Recently my PC starts automatically when I turn it on without using the on/off button. So I disconnect all devices with a socket every day (before going to sleep). Previously I had to use the on/off button to start the PC. Now the PC starts automatically, but usually there is always a black screen with an error code 501 or 502 (something with CMOS). Apparently the latest BIOS update has something to do with it, but I can't fix it and just want to go back to the old system of shutting down and starting up!

[Sneha_01 · Accepted solution]

Hi @RogerM1953 

Welcome to HP Support Community.

Thank you for posting your query, I will be glad to help you.

It sounds like you’re dealing with a couple of issues related to your BIOS and CMOS settings. The CMOS error codes 501 and 502 often indicate a problem with the BIOS settings or the CMOS battery. Here are a few steps you can take to try and resolve this:

Check the CMOS Battery: A low or dead CMOS battery can cause these errors. Try replacing the battery on your motherboard.

Reset BIOS to Default: Access the BIOS setup (usually by pressing a key like F2, DEL, or ESC right after turning on the PC) and look for an option to reset to default settings. This can sometimes clear errors related to the BIOS.

Revert BIOS Update: If the issue started after a BIOS update, you might want to look into rolling back to the previous version. Check your motherboard manufacturer’s website for instructions on how to do this.

Check Boot Settings: Look for any settings related to power management or automatic startup in the BIOS. Disabling features like "Wake on LAN" or "Power On by PCI" might help.

Inspect Hardware Connections: Ensure that all cables and components are properly connected. Loose connections can sometimes lead to startup issues.

Consider Windows Power Settings: Sometimes, Windows settings can affect how your PC starts up. Check the power options in Windows to ensure nothing is set to wake your PC automatically.

I hope this helps.

Take care and have a good day.

Please mark this post as “Accepted Solution” if the issue is resolved and if you feel this reply was helpful click “Yes”.

Rachel571

HP Support