Diagonastic programs and the restarting problem

[canserkan]

At first I had written my restarting problem while encoding on this forum.But I could not solve this problem anyway.
Now I have been decided to test my pc hardware.But I need a diagonastic program which will test my pc hardware full force and under the stress.
I think that Cpu or ram gives error while working full force.Because My pc restart only while encoding(first or second pass)
Apart from this It restart notimes.
May you suggest so program me.?
Thanks.

[theReal]

Prime95, cpu stability test, cpuburn.

Prime95 is imo the most accurate because it stops and reports on any calculation errors, even at levels where other programs might still carry on.
CPUBurn is more a heat-producing program than a memory test, but it's also worth it (you don't believe how hot your CPU can get with this! Be careful!)