I would get a 750 1 or 2gb or 750ti 2gb. The ti will run most games at 1080p low or 720 high. The 750 is a bit behind. A 400watt psu should work but, have you concidered a corsair cx450 selling new for $19.99 right now? More wattage and a solid psu. It has black cables with black shielding. Also are you sure a full atx psu fits?