Thing is, it has to be done in linux because the catalyst sucks in windows (if cpu use is high, the gpu hashrate falls).
I'm mining with full hashrates on windows with i7 cpu and 2 radeon cards.. 6 threads on LOW priority hashing DRK and sgminer in HIGH priority. Good hashrates for both coins.
With less than 100% threads (like 6 out of 8 ), it's mostly ok. In linux you can have 100% utilization on all cores and the GPU won't lose a single khash... I have a dual core and the windows catalyst combo sucks so bad that even with one thread at 100%, the gpu loses khashes... with both threads it goes down massively, even if I have the cpu miner on idle and the cgminer on high. It's just bad programming on the catalyst or the windows kernel being problematic (?).
