The MSI board I sent you can do 2 way SLI and can overclock decently. The Maximus VI Extreme is an absolute beast but also quite overkill unless you are an extreme overclocker. Overclocking not only depends on the motherboard but also your cooling and your luck in the silicon lottery. (If you get a chip that can overclock well or not.) This board is probably the best looking I've seen and about $100 cheaper than the Maximus VI Extreme.
http://www.newegg.com/Product/Product.aspx?Item=N82E16813132038
It looks really cool with the thermal armor on it and probably overclocks better than the Maximus Hero but the Hero is probably the best bang for your buck.
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131989
This is the Hero.
Both of the boards I sent you are the standard ATX size. The Extreme, I believe, is EATX. If you want to do 3-Way SLI or have 2-Way SLI and a RAID card then you'd probably need to buy the Extreme but for 2 Way SLI you'd be fine between the Hero or Formula. A motherboard won't get you any more FPS unless it's bottlenecking your hardware. (In this case none of the motherboards are a bottleneck.)
Hope this helps.