Okay so yesterday I ordered parts for a new build and I got a PC Power & Cooling Silencer MK II 950w psu but all I will only have an i5-2500k and one gtx 560 ti for right now but will get another for sli soon. So all I wanted to know is if my system will only use about 640w or so with two gtx 560 ti's (I got that calculated wattage from newegg's psu calculator) will there be any cons for having such a large power supply when a lot less is required?