Last year I purchased this motherboard: http://www.msi.com/product/mb/870A-G55.html
Video Card: http://www.newegg.com/Product/Product.aspx?Item=N82E16814102898
When I purchased this board at the time I purchased one Radeon HD 5770. Earlier this year I purchase another card, so I could Crossfire. But in the process of setting it up, I couldn't. The CCC never reconized the second video card, but Windows did. I was able to use the card, it worked perfectly, but the Catalyst CC never seemed to see the card so I could setup Crossfire through the software. I used one Crossfire X bridge to connect the cards.
I reached to a forum for help, and they told me that the motherboard chipset never supported Crossfire. But the product page for the Motherboard says it supports Crossfire. Any ideas?