jooles, chipmunk,
Thanks for your advice, I've had my computer in pieces and it is the fan in the PSU.
I think it could be on it's last legs. [Linked Image]
No worries though, I've got plenty of them here that I can use as spares.
Just a little note, while I had the case cover off, I had the TV on in the background, I happened to turn around and look at the screen and it was really messed up with all sorts of Herringbone patterns, I put the cover back on and they went away.
Just goes to show what metallic sheilding can do, eh?
I'll throw another fan in the PSU on my next day off. [Linked Image]