Hi, I just recently try the new drivers at 4k, and crossfire is deactivated. With dual 290x, I am only averaging around 24FPS, while with 15.6, I am averaging at 42FPS.
There is a reason why the CR flickering is gone, the CF profile is deactivated.
I can confirm that single card performance at 4k is better than CF performance for two 290x.
At 2160p, Beta drivers 15.6 run well with CF and average for 45FPS while 15.7 average for 25FPS. True Hairwork AA and flickering are fixed, however CF is more broken than ever.
I did the tests again this morning and it is obvious that your Windows 7 64 drivers are not working properly.
I will need to try them on Windows 10 to see if there is any difference.