Thanks a lot for your feedback!!
I found a solution for my setup, extreme simple.
Following steps worked out really fine:
- turn off vsync in-game
- turn off adaptive sync on monitor
- in Nvidia control panel just switch vsync from “fast” to “on”
- no fps limit in ncp needed
With frame generation on I get fps between 50 and 90 with Fenix a320 and 3rd party add on scenery. No tearing at all and absolute minimum off recognizable input lag.
Just change vsync setting from fast to on in Nvidia control panel made the change when switching from dx11 to dx12. 