Low GPU usage with Crossfire setup

Hi all,

Some PC info before I get started:  

- 2x R9 290s in CF

- i5 4670k

- Ample power and watercooling so thermal throttling isn't an issue

- 14.11.2 Beta drivers 

So, my issue is as follows: While I can usually get a frame rate above 60 while adventuring in the wilds, my GPUs never seem to work above 70% (sometimes as low as 40%). I do not have Vsync on and the ingame refresh rate is set to 120 as my monitors refresh rate is 120Hz and want to get as much as I can out of it as I can, so that isn't the issue. 

If the frame rate was never below 60 I could deal with it, but in towns such as Haven and Crossroads (and occasionally in particularly wooded areas) the frame rate drops to 35-40 and yet the GPU usage does not crank up to compensate - very frustrating!

I have tried using Mantle but that just screws everything up and it becomes jumpy and completely unplayable going as low as 5FPS and average 30-40 in the wilds.

Anyone else on a CF setup encountered similar low GPU usage issues? Sounds like a driver-side issue but if anyone has found a workaround that would be great.