Ok, I think I finally figured out what's happening…. As long I just restart my PC and don't run anything else both of my GPUs are mining at their highest hashrate. But as soon I start a video, or open a web browser the main one drops to like 1100h/s. Is there any way to prevent this, even if the price is a bit slugish system, I should at least be able to run a music player while mining. I know this was the case with the Cryptonote miner, bot of GPUs were at constant cca 1600h/s.