It depends largely on the games you're playing or trying to play. If you play mostly MMO's, especially games like Planetside 2 and Arma 3, you'll be murdering any CPU you throw at it, even a 6950x (we've tried, it happens). If you play mostly graphics-intensive titles (or more balanced titles) like Tomb Raider and Hitman and The Witcher 3, you'll have a fairly balanced load across the CPU and GPU.
If you just want 1000 fps in CS:GO, I'd recommend running the GTX1080 with a G3258 cooled by phase-change cooling or LN2.
Resolution and refresh rate matter quite a bit more here. If you're playing at something like 1080p 120hz, a 1060 will be more than suitable for the task. 1080p 144hz up to 1440p 120hz would be the 1070's stomping ground. 4k, 1440p ultrawide at 120hz+, etc. would be the 1080's playground.