Thanks for the replies, I did use arctic silver thermal paste, I just bought a stock 965 black edition cooler from ebay.

I bought Watch Dogs online for £3.04 and the first thing it asks you to do is shoot Maurice. Obviously controversial, I didn't want to shoot Maurice so I shut down the game and I doubt I will play it again. What a waste of money.

I think I've used the right amount of thermal paste, I watched a video to learn how to do it.

I've reseated the cpu and heatsink. I am using the cooler from the Athlon. But would this cause it to shut down that quickly, (in 10 minutes)?

What do you mean? My CPU gets up to about 85C then the computer turns off.

The heatsink/fan is properly connected.

I just upgraded from an Athlon 2 250 3ghz dual core CPU to a Phenom 2 965 black edition 3.4 ghz quad core CPU. I put thermal paste on it but the computer keeps turning off after about 10 minutes.

@PredatorRules:

The CPU temperature was 81 degrees C.

@PredatorRules:

The CPU hasn't got any thermal paste on it. Could that be the reason the PC is overheating.

@PredatorRules:

It's a be quiet PSU, I've had it for about 4 years.