There is no reason to clean out the entire driver, just install the OpenCL Package by itself, it is open cl, not the driver that makes the difference.

Only about 2 minutes of downtime and I get 3Mh/s more on Phoenix with the Phakt kernel.

In the guru3d download it is under: Setup -> Packages -> Apps -> OpenCL


More info:
I am running 11.8 Win7 x64 on a R5830. I installed the regular version of OpenCL from 11.9RC not OpenCL64.


(In the last 5 min: 24 Accepted; 0 Rejected so looking pretty stable to me at first glance.)