I have 1 2gb HD 7850 graphics card, and im planning to buy another 2gb 7850 for about $230, Im using Asrock 970 extreme3 with crossfirex suport x16/x4 config. Will there be a little performance increase in my gaming or should i upgrade my motherboard too to any x8/x8 or x16/x16 to feel the effect of dual graphics card?