http://www.ecs.com.tw/ECSWebSite/Products/ProductsDetail.aspx?detailid=1000&CategoryID=1&DetailName=Specification&MenuID=145&LanID=0
Is this your motherboard?
If it is, it has one PCI-Express x16 slow, which means it will only hold one graphics card. You won't be able to crossfire anything, well at least none of the newer cards. I think it'll be able to run a single 4870x2, though.