mmmmm flakey eh?
The highest I have to run for benching on my FX55 SD wk13 is 1.525 x113% and thats running 3dm03 at 272*13 - then my temps are zero under load.
Firlty make sure rear fan on teh mach is set to turbo and front fan set to 75% to ensure good air flow and better cooling under load.
That opty needs quite a bit of extra voltage to go higher - which surprises me.
Mav