Got it changed on the spot, managed to take a detour and sneak to the shop yesterday 

15 runs of maximum IBT gave me about 67c maximum, also there were no errors so I'm happy about that, my cpu is running at 4.3ghz. Orthos will be the next stop to make entirely sure this beast is stable, it was never perfect until I changed the ram. Blue screens were regular occurrences but I was putting it down to the overclock being too much.

Ta very much again.

It's a good tip for anyone when building a new rig, always run a thorough memory test as well as benchies to be sure you don't have a duff stick that will only occasionally show its true colours.