There has been more and more game that relying hyper threading. Meaning the more threads a cpu has, the more efficient the game will work. Standard i7 4 core 8 thread can maintain 70% on most Q3&4 2016 games, even in the old i7-2600's. If you use more thread like i7-6950, the more less the cpu usage is (around 30-35%). In my case, my 12 core 24 thread 1,7GHz (very low clock due to 65 watt architecture) can maintain most of modern game below 25%.
So far I have tried Mafia 3, Battlefield 1 (multiplayer), Fallout 4, Farcry primal, and the Division. They all below 25% with my current cpu.
My previous i5-2320 3,5GHz were working 90+% on Battlefield 1 and around 75% on The Division.
Battlefield 1 is the main reason that force me to experiment with cheap old used xeon that I manage to get my hand on. Under cpuz benchmark, my xeon only get around 10000 which is below i7-6700k, but the reality in game say differently.
To make it solid, my cpu temperature stay between 50-51c as 50c is the setting that my hsf fan start spinning. Unfortunately my cpu idle temperature is 48c, maybe its the main reason they sold it used.
Hopefully they will keep consistent regarding "more thread = more effective cpu usage".