Hello,
This can be caused by an too high temperature of your pc.
If your PC is properly designed, it's cooling system should handle the devices originally installed without shutting down, even when it operates at 100% load. This of course assumes room temperature and that vents on the PC aren't blocked or the case filled with dust.
If you've changed major components without purchasing them from the orginal PC manufacturer, your taking your chances. There's no way they're going to test all possible devices or know what might happen, so that's why you're getting the run around.
If you've built the PC yourself, you're resposible for the cooling design, since the case and powr supply manufacturer can only give you general specs. True PC manufacturers test the heat caracteristics of the critical devices like CPU and HDD under various ambient temperature conditions with the system running at heavy load for at least several hours. The temperature sensors must stay below certain thresholds to be approved for manufacture or the desgin is changed.
However, be sure to keep the vents clear of dust and pay attention to the sounds of the fan(s), since they indicate that heat is increasing by speeding up in some cases and should normally idle quietly.
Best regards
Sandra
Team Spybot