So basically, the problem is the following: while playing PUBG (and yes, it's only pubg that has this issue), my GPU is being used 100% (i saw that in task manager). Also, the fans are making very much noise. This, however, does not impact the game itself. I mean I can play it just fine, as if nothing has happened. I've never experienced shuttering or in-game lag.
I've got the latest Adrenalin Software and I am having this issue since August 2018 and still haven't figured it out.
3D Settings are all on default / let the application decide what is best for it working properly.
The in-game settings DO NOT matter. if everything in on very low is all the same as if everything is on ultra.. just a bit of difference in FPS but that's it.
Here I have attached a short video that will show what is happening exactly. In the background you can also hear the noise my pc makes while pubg is opened.