claymore, my 8g rx480 shows memory usage of 60% and GPU usage of 100% with drops to 0% several times a minute. Do you think it might take another thread?
GPU and memory are busy completely, you can check it by starting two miner instances, you will not get more speed.
Due to PoW implementation, GPU cannot utilize all its resources, so you don't see 100%.
what is the reason why my hashrate drops
i have mixed gpu
2x280x = 220 each
2x480 ref =210 - drops to 185
1x470 black ed - 209
Probably the reason is drivers, miner compiled with 15.12 and 16.11.3.