I have an Alienware x51, which has I believe a 240 watt power supply? it uses an nvidia gt g545 gddr5 gpu. I want to upgrade the graphics card to maybe either the gtx 750 ti, gtx 660, or the gtx 760. I know that it needs a larger power supply for any of these cards, but I don't know what power supply can fit in my mini itx case, or if that's even an issue. I also don't know if the gtx 760 will fit in my case. I know that people have been fitting in the gtx 660 and 670's in their machines but I just don't exactly know what card can fit in my case.