X51 CPU Overload?

I have just bought an X51 that was delivered yesterday. Straight out of the box it was freezing after a few minutes use (just installing stuff not even gaming!). After clean installing all the nvidia drivers (believing the problem to be down to the GPU drivers) it was still freezing after 2 minutes of gaming or about 10 mins of surfing. If I was loading 2 youtube videos it would just melt. I was running mass effect 1 fine on ultra for about 2-3 minutes then it started freezing and sounding like skrillex. I checked task manager and all 8 threads were at 80-100% usage!, I minimized the game then it began to stabilize, after going back to the game it happened again. I have the X51 i7 3.4 GHZ - 8GB ram DDR3 - nVidia GTX 660. These specs shouldn't even break 20% per thread but they do drastically. Anyone with suggestions? Also how do I go about complaining to dell as my package as a whole (optx monitor, x51, tacx mouse and headset) came to £1600 - which would be fine if it worked correctly!

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