I achieved an overclock of 4.3 Ghz with a Vcore of 1.3V. I'm usually able to play all games at ultra with reasonable fps (depending on which game). For example, Bioshock Infinite : 72 fps (at ultra), Shadow of Mordor : 53 fps (Ultra with Medium textures) and Valley Benchmark 1.0 : 40 fps (with extreme preset). I rated the Fractal Design Define R4 3/5 because I got some problems to open it at the beginning. It didn't open easily but at the time I built, it I didn't want to return it to the manufacturer. Finally, the Asus Z87-A is awesome, but I got to give 4/5 because the Asus Suite III causes MANY BSOD to my system, so I just ended up overclocking my CPU manually...I think it is better to do it this way, don't you think ?