Stuck at around 300 khash/s on my 7970 atm

running factory clock settings, using reaper.
worksize 256
aggression 13
threads_per_gpu 1
sharethreads 18
lookup_gap 2
gpu_thread_concurrency 8192
have tried alot of diffrent clock settings/thread conc, the best i managed around 500khash/s.
Any suggestions?