A GTX 1060 and an I5 6400 are a good compliment to each other, neither will be a bottleneck in performance. I build gaming PC's for a living and have extensively tested this exact combo. For 1080p gaming, this is a strong performer. Easily 60 FPS in The Witcher 3, Fallout 4, Borderlands 2, Crysis 3, Shadow of Mordor, Star Wars Battlefront, Battlefield 4, and many many others I have tested. If you are having issues with performance on these parts it most likely is down to heat throttling the GPU, power supply issues or some other software-based problem.