I run two PCs at home, one for gaming and one for internet etc. and the latter PC (which is older) keeps throwing me some wacky fan error when it reboots. Any idea what the hell that is?

Ah yes, the “wacky fan error”.

Way to edit a classic thread title there Bill. :-)

As for your question, I’d assume it’s pretty self-evident that there is a problem with the fan, meaning it may not be spinning or not spinning at the rate it should be. Most computers have fan monitors built in now so that you are informed when one goes or is getting ready too. The obvious thing would be to check all the fans in the case and make sure they are all operating.

What Sarkus said.
If the fans seems to be doing fine (visual inspection), then get some temperature monitor and look at temps - if they’re fine too, then it’s just a BIOS setting that’s wrong (When I switched to water cooling I couldn’t boot because the BIOS was reporting a CPU fan failure).