And just for your information, my X2 cannot pass Prime more than 40 minutes with my Nforce 3 Ultra system, one of the Prime always fail while the other still running.
But that not happen with my Nforce 4 Ultra system + Opteron. I'm not sure that because of the CPU or the whole system, since I already sold my Nforce 3 system, and didn't have any change to interchange my peripherals .
That's a clear heat buil-up problem. Nothiong to do with the mobo or any othe component in the system per se, except the Heatsink and cooling arrangements.