Hi all, I currently have one Sapphire 7950 clocked at 1100MHz core and 1375MHz memory hooked up to a 2560 by 1440 Achieva Shimian. I love the setup but I feel as though one card isn't enough to hold 60fps in all my games with the AA turned up. This: http://www.newegg.com/Product/Product.aspx?Item=N82E16813138344&Tpk=tz68k+ is my motherboard which supports Crossfire but the second card would only be running at 4x speed. Is that going to slow things down a lot and is a 620W Seasonic going to be enough even if I lower the clock speeds to say 1GHz. Thanks in advance.