@Friz wrote:
(...)
The crashes occur randomly during the daily use. It not depends from the load of the system, I did a lot of stress test and the system don't shutdown. I switched to another cpu like mine (my friend cpu) and the problem dissapears.
Sorry to say this, but you just answered your own question. Looks like a CPU issue, is it under warranty? If so, I would try to RMA it.
If not, try upping the core voltage a notch using offset mode. Start with +0.05v
Upping the voltage will also make your CPU hotter, so monitor the temps carefully.
The Englishman