Quote Originally Posted by o_O View Post
Quote Originally Posted by Grinenshire View Post
Check that your fans aren't too dusty. This happens quite a bit especially with laptops.

As for the test, do an experiment. Run a high-end 3rd game at full quality and see when it turns off. Then restart the PC and leave the empty desktop open for a bit. If it goes off on the first but not the later, it's the overheat.
The more demanding the task, the more power your components will draw from the PSU, so this test won't work.
I think it would actually. The difference between the power demand and the overheat is quite simple really. Time. Once you start a high-end application, the power will be immediately needed in all of the components, save the cooling system, and thus you'll see the effect right away. If it is the overheating, you'd still have to wait for a couple of minutes for the hardware to heat up to the level where it starts overheating. Either way, you should see that it's not the PSU once all the fans are working on full power and the PC is still on.

Apart from that, what Mirage said about the boot-up lag.