Prime 95 sometimes works, sometimes doesn't.

[The_Lurker]

Here's a few problem. Sometimes, i could run Prime 95 for hours on end at 900mhz and 1.85 Volts. Then i decided to back it down a bit and try it out. Prime 95 ran fine, but i crashed a program, so then i raise the voltage back to 1.85, and this time, Prime 95 can't run for more than 2 hours. So i'm scratching my head now. Back it back down to 1.8, Prime 95 gets an error 5 minutes after i start it. Doesn't round off? Any ideas? i'm back at 1.85 and it seems fine (been running prime 95 for 20 hours or so now)