Hmm, I'll have a look on Akasa's site for install instrucions as none came with it. I didn't think it could go on a wrong way round..... :edit: Found
this. Am sure that's how I was doing it. Will try removing the PSU to get the HSF installed better tonight. I can now see how it would be installed wrongly as it looks to fit over the socket top (sort of a raised bit).
But how would it recognize that it wasn't on right? Or would it get that from the heat build up in the CPU? Would the same thing happened if no HSF is on (not that I'm gonna be stupid enough to try that!)?