If he'd run it at 720p then his cpu usage would go up together with frame rate and not the other way around.Do you run the game at 720P resolution?
The point is that there is something fishy about that screenshot because my 6700K never reached anywhere near 90% when playing GTA V maxed out at ~100fps.
edit:
ok my bad thought it was GTA V as someone said it was.
now I either hope that OCUK ship to my beautiful vienna or that I will learn the magic called OCing hehe.