Hi; I think I could use some help here

I am experiencing a rather weird situation atm.

I'm running my CPU at 3.6Ghz (9x400), and it is perfectly orthos stable when I test in small FFT's. But when I try doing large in-place FFT's to stress some RAM as well, it errors at about 8 minutes each time.
I have now ran memtest and it seems my RAMs are perfectly stable as well :O

Here's my voltages:

vcore: 1.450
vMHC: 1.55
vFSB: 1.40
vDIMM: 2.05
vICH: 1.05

I'm about to try 1.65 on the vMHC and 1.20 on the vICH now, think that might be the problem?