I have 390x and a lot of problems with core clocks under crimson too. I had to revert back to 15.11.1 CCC. Reported to AMD twice, now hoping for some fix in the near future. My problem is that under CCC my core clocks in a lot of games are slower then under Crimson. Fore example fifa. Non demandig game, under CCC 550-850 MHz(smooth), under Crimson 350-600 MHz. Problem is, that it is not enough for the game to be smooth. Same problem under a lot of other games. Of course, if I'm running the witcher 3, with max settings, it's trying to achieve 1100 MHz, but it keeps jumping to 600MHz area and couse stuttering too. I hope for fix, but there are a lof of guys, who don't have these problems :/. If AMD will let me down in this, I will jump back to green camp. I'm just not happy with this situation.