Hardware errors in either CPU or RAM, what to do?

Solution 1:

Can anyone tell me what this means?

You have a hardware issue that needs to be addressed - likely memory. typing MC15_STATUS[Over|CE into google, second hit is from the unraid forums which may me helpful too.

Is this something I need to worry about?

Absolutely! Ignore hardware errors at your (data's) peril. I would be getting that system out of production without spending time asking the internet if this was an issue I needed to worry about.

Use something like memtest86 to test and diagnose the location of the issue.

Solution 2:

In your case I'd read the IPMI BMC event log, e.g. with ipmiutil sel. It should show the details about errors, in my case it showed even the particular memory slot location where the faulty module resided.