The above is your problem, you should have installed the 11.11 Catalyst driver package and not "upgraded" from the included AMD APP SDK runtime v2.5.
To get the most performance with SDK >=2.6, you'll need to do some specific miner kernel optimizations and use different memory clocks.
I'll share my phoenix 1.7.4 command lines demonstrating the differences you'll need to get max hash:
SDK 2.4-2.5: 295MHz memory clock
phoenix.exe -u http://user:pass@us.ozco.in:8332/ -k phatk2 VECTORS AGGRESSION=12 FASTLOOP=False WORKSIZE=256 PLATFORM=0 DEVICE=0
SDK 2.6: 1000MHz memory clock
phoenix.exe -u http://user:pass@us.ozco.in:8332/ -k phatk2 VECTORS4 AGGRESSION=12 FASTLOOP=False WORKSIZE=64 PLATFORM=0 DEVICE=0
The AMD control center won't let you do the clock/voltage/fan changes you need, you should use a third party utility such as Sapphire Trixx or MSI afterburner to enable higher overclocks and to set the GPU fan speed much higher at lower temperatures.