First off, I have the Alienware X51, I purchased it early June, it has the Intel i3 processor. I already know the processor I want to upgrade it to, but I'm having trouble with finding a graphics card that is compatible. I was looking at the GeForce GTX 770, but I looked it up and the power supply won't work, and apparently there is no way to fit a newer power supply into the X51's case. I currently have the GeForce GTX 645 in my X51. If you could give me a good graphics card that will work with this machine. That'd be very helpful, I'm willing to pay at least 500 dollars for a new one. Thanks.