Apparently your issues is common,your graphic card is not the problem, you can see this https://www.youtube.com/watch?v=d0Xqe73qaE8

You need a CrossFire profile because your graphic card have 2 GPU in it.
Now you have to hope that AMD will release a proper CrossFire profile for your graphic card for this game or maybe you could try a profile of another game like crysis 3 because they share the same engine (aka crytek engine).