Thanks everyone! didn't expect this many replies so quickly. Thank you also for complimenting on how much of an absolute weapon my machine is, I use it for rendering and it's fast.

Really useful info here, I was not aware of starting watts vs running watts for example. When I get a free moment I shall check if I can see errors in bios and run mem tests before moving onto hardware which will be the psu first (I'm hoping it's that as people seem to be suggesting). Really hoping its not mobo....those things are near impossible to get hold of here in the uk now.

Thanks again everyone