Video Crashing with crossfire 280x

[Thecowtamer]

I bought a sapphire 280x about 3 months ago which worked great and never had any problems with it. I purchases a second sapphire 280x and put them in crossfire today. The games will run normal for about 15-20 mins and then my video will freeze but I can still talk in the skype call. What could be causing this problem? I did enable crossfire and Im pretty sure I downloaded all the correct drivers. Any ideas would be great.

 

[Thecowtamer]

I should add that my whole computer becomes unresponsive at times too. I don't know what is wrong.