I recently upgraded from an i5 to an i7, specifically the Intel Skylake Core i7-6700, 3.40GHz, Quad Core, LGA1151. It uses 0-5% cpu on idle, 5-10% when just firefox is open, but then jumps to 100% when I try to run a game. I tested it mostly on Dying light and Shadow of Mordor, with both of them the cpu was fine in the booting and opening credits and stuff, but then as soon as the main menu shows up it spikes to 100, when I minimize I see it drop to 20% or something. I also tried it on Grow Home, but that had 100% as soon as the intros started loading and Terraria, Terraria worked fine, but had a CPU usage of about 70%. I also recently got DDR4 RAM, 8Gig, that also jumps to close to 100% when I try to run a game.