Vega64 - Claymore: Fan Speed and OC unpredictable behavior

Good afternoon,
i need an help because i want to change my Win OS with Hive OS but i have some problem with Fan Speed setting and OC too.
If i keep default parameters, the speeds of fan stay around 40% and my cards (12 Vega 64 w/samsung) temperature became very high.
If i setup in Claymore -fanmin 100, my fan reach 100% speed always but is very expensive.
When i try to change something in OC form and restart the miner, the speed goes to 7MH/s on all the video cards.
There are some profile/settings/guide that i can follow.
Thanks in advance