Your board will work with crossfire, up to two gpus. As for powering them many come with an adapter that plugs into two molex 4 pin plugs. Also it's usually better to run one card than crossfire unless you are upgrading one you already have. When you run multiple gpu's they don't run at 100% efficiency like one would on its own. I would just buy a 6950, then you can buy something better later on and crossfire the two of those.