ASUS Rampage IV Extreme
 

There is a review of the ASUS Rampage IV Extreme at Overclockers Club today that is definitely worth checking out. Here's a quote from the full review: For the gamer, there are the four PCIe 3.0 ready 16x slots that support both NVIDIA's Quad SLI along with AMD's Quad CrossFireX configurations at 16x/8x/8x/8x, to get the most out of the available graphics horsepower that can potentially be installed. Adding a fourth card limits availability of the connectivity at the bottom of the PCB, but there are sacrifices to be made for four video cards.

http://www.hardocp.com/news/2012/03/...ge_iv_extreme/