We can also add that in the things that matter with this gpu's (higher resolution, multimonitor, 3d) HD6990 is the better choice performance wise.

1920x1080/1920x1200 --> too low for a dual gpu.

They need a more expensive "6GB" 590 to do something. And thats another problem of not using 256bit, if they want to compete they need to put more memory than necessary.