Making an i7 920 more stable, help!

My i7 920 is running at 3.6 seemingly well, and when I run the 'blend' and 'in place large fft's' tests it runs them fine. However, when I run the maximum FPU test it only lasts 5 minutes before a BSOD. Temperature is not the problem as no core goes higher than 70C.

Here are my BIOS settings:

X.P.S Profile
CPU Voltage: 1.35V
QPI/DIMM Core: 1.28V
DIMM Voltage: 1.64V
BCLK: 180

What should I change to make it more stable?

i7 920 @ 3.6
ASUS P6T
GTX 285
1x6 GB Corsair XMS3 9-9-9-24 @ 1433

Thanks.

OK, thanks. Also, how should the QPI voltage be increased relative to CPU voltage? I know at 1.35V CPU voltage that I cannot raise the QPI more than 1.32V or so without being unstable. If I raise the CPU voltage will I be able to raise the QPI and still be stable? If I can why should I, what does higher QPI do exactly?

Thanks again

3.0 is enough to drive that GTX285 well. Don't get greedy, back off BCLK untill you are stable.
Consider using a oem cooler if you want to pusk the overclock.
How high you can overclock will differ from sample to sample.