My MSI 280x has only 6.4 Mhash/s.

I'm using Win 8.1 64 bit. Catalyst 14.6 RC2.
My config:
sgminer3s.exe -k 3s -o stratum+tcp://one.suprnova.cc:2323 -u x -p x -I 19 -w 256 --thread-concurrency 8192 --lookup-gap 2 -g 4 --shaders 2048 --gpu-engine 1150 --gpu-memclock 1500 --auto-fan --gpu-fan 55-80 --temp-cutoff 80 --temp-overheat 75 --temp-target 70 --no-submit-stale --no-pool-disable --api-listen --api-allow W:127.0.0.1 --expiry 1
