I’ve a real strange Problem:

I Overclockt my AMD 1400 to 1610Mhz (11,5 x 140). It runs stable for hours under full load, (about 2-3) then my system crashes! The monitor simply get black and my USB Devices loos their electrical power! The real strange thing is, I can reset the system immediately and it runs again for 2-3 hours! I experiments this problem only under full load. The temperature of the CPU never extends 55°C.

Any ideas?

Rest of the system:
ASUS A7V133, GeForce256, 1024MB RAM Infineon, 4xIBM 80GB, 400W Powers supply.

PS.: please excuse my bad English!

Its possible with the oc and 4 hard drives that the power supply is on the edge. I agree that 400w should handle it, but no power supply produces exactly what it claims to so if you have another one around I would try it. Other than that you might try swapping out the ram to see if that is the culprit, and of course it could just be that the motherboard can't handle 140mhz fsb reliably.

It does not sound like a heat problem.