Help! Continuous failure of Prime95!

Well, I ran into some problems with BSOD randomly after about 3 nights of idle (I use my 2nd computer a lot and the other one just idles). So I decided to run Prime95. Here are the specs
Athlon 64 (Socket 939) 3500+
MSI Neo2 Platinum
Corsair XMS PC3500 2x512 (BH5)
WD 36GB Raptor
Fortron 530W PSU
Radeon 9800XT
With this, it failed at about 2 hours. So i swap out the power supply with a 420 Thermaltake. It then failed at TWO MINUTES! What do you guys reccomend I do?

UPDATE: I Ran Memtest 86+ on my memory for 24 hours, with ZERO errors, so I Was wondering if anyone else had some tips or suggestions, Thanks!

 

see if you can get a hold of a multimeter. check the voltages of the 12v line UNDER FULL LOAD. if it's 5% off spec, then you'll need a new power supply. A fortron 530 watt will fit.

 

yeah but thats what i have. I just got done swapping it with a 420 thermaltake, and its just as stable with the fortron. However, I swapped out the memory (its corsair BH5, that hasnt been sold for quite some time after they stopped producing BH5, so this is what im thinking is the problem because i hear S939 isnt too stable w/ a lot of memory.) with some OCZ PC3200 Dual set.