This issue if you search the forums has been brought up many times. There are no official fixes for this nor has any eta ever been given on when the cards drivers will work at default speeds.
The only things I have seen people say that may help is underclocking and/or under volting the card. Some say (again I have zero experience here) that doing this even though the card is running slower, it no longer overheats and throttles down thus actually improving performance.
On my RX 580 I get similar issue but can resolve this with lowering the maximum temp on the temperature slider to 70. Vega users have reported that this does not help, you could certainly give that a try before down clocking.
This AMD support article may help you: How to Tune GPU Performance Using Radeon Wattman and Radeon Chill
Yes, sort of sounds like it can be addressed with a custom fan profile. My Vega LE can get that hot if ambient temps are a bit toasty. I typically run the fan on that one up to 3400rpm and have the target temp as 65/70c. Of course this means the noise goes up a little bit but that can be fixed with headphones.