I have win 7pro 64bit. board is gigabyte GA-MA790FXT-UD5P. CPU amd phenom11 x4. 3.4ghz black. (965) 16gb memory. 1, 250 gb ssd. 1 terabyte sata drive. PSU is MAXCUBE BLITZ 550W. 2, LG multi dvd writers. multicard reader, video card. fans, 1 front/1 rear. I wish to upgrade my graphics card NVIDEA GeForce GT 220, to a (probably) asus GeForce gtx 660 dc2-2gd5. (if it fits the board.) or something in the gtx650 range, which is shorter in length. both reguire 150 watts, both reguire 6 pin for additional power, which I have. i'm guessing that the new GPU will require about 100 or so extra watts than the currant one. have I got enough power.