Stuttering and bad performance with good PC

There is a setting that let’s you pick which GPU to work with and which fixed this for me on a similarly spec’d PC get 60fps now on ultra. Async compute

Wich setting ?
The GPU selection in Gears video options ?

It do nothing in my case.

Before rolling back to the old driver, in MSI afterburner I could see that my GPU don’t go under 30/40%
Now with the 398 version. It go to 100%.