my randomly shuts down after about an hour or so and when i try and turn it back on it lasts about 1 minuit then it switches off again. after about 3 times trying to turn it on it beeps about 4 times then it says "cpu overheated" then some windows restore stuff then it switches off, at first i thought that it could be that the processor fan wasnt working because when i took the cover off the metal bits around the fan were very hot. i dont know what to do about this and i have no idea what is not working. i dont know why the cpu is overheating because the fan that cools the processor is spinning. if there is a fan on the power supply i dont think it is spinning because i cant feel any air coming out. my motherboard is an asus p5gdc and there is a a nvidia geforce pcx 5750 plugged into the pci-e x 16 slot and there is a modem which i have never used in one of the pci slots and two 256mb sticks of ram in the blue slots and thats all.

there is a fan in the back of the case, a fan covering the processor i think there is meant to be a fan in the power supply and there is a fan in the side. does anyone have any idea what this problem is and what can i do about it.

it normally shuts down when im playing games. The only games i play are the sims 2 and halo, my problem first started when i was playing sims 2, the first times it happened it didnt shut down, it only restarted. then it started to shut down and keep shutting down with the cut out time becoming shorter and shorter. anyone had this problem before?

What i would try is remove the side cover to you case and run the computer like that ,it won't heat up as fast ,also just because the fan is spinning doesn't meant it spinning fast enough ,also you power supply needs a fan ,if its not working it will eventually burn out the power supply.if computer runs with the side off ,then its time to buy some new fans

If you can try going into BIOS. Most BIOS systems will tell you the CPU tempature and will actually shut down your PC if the CPU is getting to hot to prevent damage.

My CPU normally runs around 95-110 F when standing idle and playing games. Automatic shut down is around 140 F.

If the issue isn't with the fans:

The thermal transfer compound which is applied between the CPU's surface and the heat sink can dry out, or the heatsink itself can work itself loose; either may cause the computer to go into thermal shutdown.

Remove the heatsink from the CPU and make sure there is a decent covering of thermal paste on the CPU. If not, or if the paste appears dried and cracked, remove the old compound and apply new compound. "Arctic Silver" is probably the most recommended brand of thermal compound.

If you are going to do as DMR is suggesting you may as well plan on cleaning off the old thermal compound and install a new film, and I also agree that Arctic Silver is the way to go.

Another thing you could do is to download Everst Home Edition, this will allow you to monitor the temperatures, and fian speeds whithout having to go into the BIOS.