Need help from the OC guys. (weird problem OCing Q9550)

CPU: Q9950 cooled with ASUS Triton 79
VGA: GTX295
MB: MSI P45 Platinum DDRII
RAM: 4x(1Gb 1066 A Data Extreme Edition)
PSU: Epsilon 800W FSP
HDD: 2x(1TB 32 MB) WD
LCD: ASUS 24* 1900*1200


hey everybody
I'm not new to this but I don't have a lot of experience, I'm having problems ocing my q9950
I was hopping of reaching ~3.71Gh
the problem is with prime 95 (the blend test) cause the cpu is always stable in the FTT test @3,3\3,4\3,5Gh of course after raising the Vcore.
but in all cases the blend test always fails after 2-11 min and it become instant @3.5
and @3.71 I get blue screen
I tried everything I raised the VTT(1.31), DDR voltage(2,3), MHC(1,35) and even the south bridge
I set the RAM timings to auto and by the way about the RAM frequency I can set the multiplier only at 1.20 and 1.33 any other option and the system wont boot up or I'll get a blue screen.
it kind of depends on the FSB, cause on certain fsb I can boot up @1.33 but not always.
I changed the RAM many times but I still got the same problem
can anyone of you OC guys help me with my problem