Hello and welcome to the forums
+1 to what mindless said,it support CrossFire but at 16x4x which isn't good for gaming and it will give you a noticeable lower performance compared to dual 8x and dual 16x:http://www.tomshardware.com/forum/245454-33-crossfire-faqs
"A note about Motherboards:
Dual 8x is a very good configuration too,it doesnt have alot of difference with Dual 16x and its cheaper too.
Chipests like Intel P55*,Intel P45 Nvidia 750i SLI, Nvidia 650i SLI,NVIDIA 570i SLI, NVIDIA nForce4 SLI, ATI Radeon Xpress 200, Intel 975x and ONLY few Intel P35 boards(Like ASUS BLITZ FORMULA and ASUS BLITZ EXTREME) support Multi-GPU at dual 8x mode.
The last one is 16x 4x, this one is the weakest and doesn't perform very good compared to dual 8x or dual 16x,so i won't recommend it for Multi-GPU configuration. Intel P35 and P965 chipsets support Multi-GPU at 16x 4x mode.
Here is a good review which compares CrossFire performance between dual 16x,dual 8x and 16x 4x:http://www.tomshardware.com/reviews/crossfire-pci-express,2095.html