Use MSI afterburner and check cpu and gpu use in game. Very much game dependent, but if the GPU is less than maxed you will see an increase across the board with a CPU upgrade. If the GPU use is maxed, you probably won't get much better in max fps, but will likely see improvements in avg/min fps (that is assuming the CPU is occasionally limiting performance).
If you are running maxed out then that's not bad actually. Turn the anti aliasing to 1x. All it does is make things look too soft anyway. Turn off sun spot caching too. Pointless waste of GPU Ram.
How does that compare to your 1070ti? If you slide that old girl in there what is the performance delta at 1440p everything else equal?