Hi everybody,
I don’t really know where to post this topic exactly: It is related to my 8K-X specifically as well as to PiTool as well as maybe to my Truck Simulator (so Games). So in the end I decided to put it here. Hope that fits more or less 
I once again and as always 
did a couple of further tries to improve the FPS with my 8K-X in Euro and American Truck Simulator during the last weeks and months. Especially, I am still trying to get FFR to work properly with them as I hope(d) to achieve some significant FPS increase.
But unfortunately, my observations and the results aren’t as clear as expected which make final conclusions and decisions on how to continue a bit difficult:
FFR so far doesn’t work in SteamVR mode with ParallelProjection (PP) 
FFR works in OculusMode without PP 
=> So, FFR not working in SteamVR mode perhaps is related to PP that has to be enabled there.
But much more interesting is the impact on power draw for the graphics card and on FPS output. As we say in German “an image says more than a thousands of words” :
I did a second trial in Oculus mode only, opposing here w/o FFR and with FFR:
=> On the one hand, I generally can understand why FFR activated and working may draw less power.
On the other hand, I cannot really understand why there is no positive impact on FPS at all…
Furthermore, as long as FFR ist deactivated, there is no real FPS difference between playing the truck sim’s in SteamVR with PP vs. Oculus mode without PP.
And: The GPU usage is always at the top independent from any specific scenario. Also a bit weird, in my eyes.
Open for discussion as I don’t really know what to conclude out of all this - except the fact that these observations are annoying and not satisfying at all. Just a lot of “why”-questions, but no idea what to do with it