For me the problem is persistent on Win10 on several platforms: 4,5 and 6 cards on Asrock MBs (h81 btc r2.0, anniversary and B150) mostly 470 REFs, but also 480REFs.
Apparently it also happens on non-REFs (Asus) rx480 and rx470.
All cards run UV and bios modded.
Non-Polaris cards are not affected.

Any advice is appreciated.

EDIT: it can run for hours before it will jump to 100% for no apparent reason. Also various forks are affected (wolf's xmr, zawawa's GG, nicehash, etc...)
Again, it happens ONLY on CryptoNote...

P.S. ohh and I do run stable setups: