You could try a bump in CPU VTT. Not all G0 Q6600's will do 3.6, but your close if it will run 25 mins of Prime. Next time you run Prime, set it to run Small FFT's which test mostly CPU, that way if your CPU is not stable you do not have to sit through all the large FFT tests, which mostly test memory. Speaking of memory, what speed to you have it running at??