It is most likely your ram...If using the r7 Apu, get ride of your 1600mhz ram and get some 2133 or 2400mhz ram. Your gaming performance will improve up to 50%!
I have the same setup with 16gb of 2400mhz ram, and the Apu is blazing fast...3dmark scores for skydiver and cloud gate were 6760 and 8015. That is pretty amazing for integrated graphics card.
Btw, hope you over locked the CPU and Apu, as the chip runs very cool, and easily overcloxks...I got mine to 4.4ghz at 1.4v and 900mhz for Apu. Runs cool as ice with stock heatsink.