What should I trust?

At 1.92v, Prime gives me an illegal sum output, but I can run both CPUBurn and Toast at the same time for 24 hours with no problems... Should I consider my rig to be stable?

BTW, temps get much higher with CPUBurn and Toast then they do with Prime....

Go with Prime95,

now I'm not familiar with what techniques they use with CPUBurn/Toast, but I suspect the programs only heat up the CPU as much as possible, they don't check if the CPU does any correct calculations.

Prime however, does. It calculates different values and when you get an error it means the CPU has calculated something wrong.

Now, especially since I see you're folding, you shouldn't use it when it's calculating wrong. Since you would send back wrong results. Wrong calculations could also lead to strange behaviour in games and sometimes crashes..

So I'd look into it and try to remove the error.

stable

Could be memory or CPU. Prime uses both intesively, and I've gotten errors before that were casued by my ram timings.

Thanks for both your replies. That's what I was also thinking sirtoby.

My RAM should be able to handle some pretty good timings (Corsair PC3000 C2) but I'll try lowering them to see..