CPU: i7 4770 (taxes excluded, ie not overclocked)
GPU: GeForce GTX 770 4GB
16GB RAM
Playable between high and medium. The "Ultra" enjoy owner of a GTX 980 or even Titanium X and faster CPU.
Some regulators should put something down (grass detail medium shade medium reflections on high rather than ultra).
Discussions from which FPS rate (frames / sec.), A game runs smoothly, there are also to Hauf.
Quiet games need fewer frames, or to put it more clearly: A game like "The Sims" is clearly with 30-35 FPS and looks clean and smooth out, in a racing game you have to differentiate. Permanent screen change, the number of opponents while overtaking, pivoting cameras in the replays, changing weather conditions etc etc blah.
Hands down: A setup with at least 60 FPS is the program, otherwise the sense of speed is not 1: 1 over.
My personal conclusion: Dear renounce a few minor details, but a smooth gaming experience.
Have fun!