First select a CPU. Intel or AMD. Ok you selected Intel, that's good. Now pick a generation. Haswell or new Skylake. Ok you selected Skylake, that's good. Now decide if you want to overclock. Ok you selected no, that's good because it's largely a waste of time since Intel CPU's are already great performers. So you want an H170 motherboard and a i5-6500 CPU for a gaming system. Seriously though, the H170 and i5-6500 are a great base to build a gaming system from. If you want to overclock then a i5-6600K and a Z170 board is what you need.