Trial and error mate, I set for 45nm 0.630 for both and test Vcore, then I try to set one notch Vcore lower and mess with GTL 's up and down... in my case core 1 always capped out, so I tried a bit higher and settled on 0.645... runs linpack test flawlessly and survived OCCT 2 hor CPU test too... stable enough for me... I'm no mathematician but I've read that most 45nm CPU's tend to like to be around 0.8...