As you didn't say if the computer was a tower or a laptop, I'm with the rest of the group in general.  My older laptop used to overheat and shut down until I bought a cooling pad for it. Walmart sells them, they are around $25.00US, and they plug into the USB port.  It's a pad with two fans that pull air around the base of the laptop and push the hot air out the back of the pad into the atmosphere.
One of the best buys I've made.