Having an 8 core FX with a healthy overclock pushing a 780ti at 1200p ( 60hz) I rarely play games at less than ultra or very high settings . So I've never really bothered to experiment with lower graphics settings ( don't want or need to use them).
At the graphics settings I usually use, I've seen fps increases setting affinity for the game going from 4 to 6 to 8 cores but nothing like what I saw when I removed the gpu bottleneck by going to the other end of the spectrum.
I did a "mail route" benchmark on the Crysis 3 welcome to the jungle level at the "low system spec" setting, this was after the enemies had been eliminated, in order to take the variability out of the test.
I put the cpu back to stock clocks and used 1920x1080 resolution and ran a series of tests using 1 to 8 cores
The spot I chose is one where there is something in the background that really throws my rigs for a loop at the very same spot every time , establishing a low that I don't recall ever seeing in the game in other places ( may happen I just dont recall ). This happens regardless of what setup I am running ( Ivy , Haswell , FX ). I purposefully did this so as to produce as wide a difference between minimum and maximum fps as I could.
I expected to see good scaling, but frankly I was astonished. Number of cores used is the bottom series on these charts.