I have a 4790K OC @ 4.6GHz on my Asus Z97 Deluxe 16GB Ram mobo with Asus Radeon R9-290 OC
On my right second screen I have CoreTemp Gadget (yes it works with 8Windows gadget s/w).
I can in real time by just throw an eye over to se my CPU-load on every core as well as its temps.
I'm Playing BF1, FarCry 4, FarCry primal, GTA V, and amongst the most demanding - Crysis 3
Only in Crysis 3 can I see CPU load on all its cores go up to about 70-75% on very high graphics settings.
In all other games the individual core loads is approx 30-40%
So Your i7 4790 @ 3.8GHz should do just fine for the moment.
Best regards from Sweden
Ok.