Crossfire question

Hello Guys and girls,

I was hoping you could give me some details on a specific question I have.. Can Crossfire be used exclusively on some games while other games rely on one card only?

I ask this as I am thinking of making the purchase of an additional 280x but I do own one or two games which do not work well with crossfire or so I've read, but other games have full support.

So I wonder, can a profile be set for specific games to not use crossfire or is it the other way around and games will not use crossfire unless instructed to?

Thanks!