For bang for the buck gaming, the i5-4690K with a ASUS/Gigabyte/MSI motherboard (~$200) and G.Skill Trident X DDR3-2400 kit is impossible to beat. The X99 and DDR4 platform has major bandwidth advantages, but the price is not worth it especially for gaming.
Don't believe games can't use anything better than DDR3-1600. It is a common misconception. DDR3-1600 is standard/basic. Are you using a standard HD 7570 GPU? Are you using a basic i5-4430 CPU? If not, then there's no reason you use normal speed RAM for a high end gaming system.
DDR3-2666+ becomes too fast for a stock CPU, so you don't experience much gain unless you overclock the CPU. As a result, DDR3-2400 is perfect for Haswell and most high end gaming systems.