Is your Processor getting adequate enough cooldown while running high performance? If the Processor reaches critical temperatures It will automatically freeze or shutdown. You can usually find this in the BIOS settings as to the temperature it will engage or if you wish you disable it (NOT RECOMMENDED) I suggest working towards a better Heat - Sink, Better Air Circulation Myself. Also ensure the Cooling Grease between the Processor and the Heatsink is Not Skimmed on one bit, It will FRY your Processor to a point of no return if not.
Hope This Helps Ya.