My gpu with my cpu

Solution
The answer is always "it depends". We need to know what you want to do with it to give a real answer. Gaming?, HD, QHD, 4K ? 60 fps good enough or you are shooting for 144fps because you're into e sports, what's the deal. Sorry but there are way too many questions asked like this with no real info to go on.

Anyway just to play games and have an enjoyable experience all you really need is an i5 or ryzen 5 and a 1070, if you want to spend more than that then go for a better graphics card, and if you still want to spen more or really are aiming for those crazy high frame rates then go for the i7.

Bear in mind intel is rumoured to be releasing 8 core CPUs very soon, and Nvidia just released the RTX series although they seem too expensive...

Dugimodo

Distinguished
The answer is always "it depends". We need to know what you want to do with it to give a real answer. Gaming?, HD, QHD, 4K ? 60 fps good enough or you are shooting for 144fps because you're into e sports, what's the deal. Sorry but there are way too many questions asked like this with no real info to go on.

Anyway just to play games and have an enjoyable experience all you really need is an i5 or ryzen 5 and a 1070, if you want to spend more than that then go for a better graphics card, and if you still want to spen more or really are aiming for those crazy high frame rates then go for the i7.

Bear in mind intel is rumoured to be releasing 8 core CPUs very soon, and Nvidia just released the RTX series although they seem too expensive to consider just now.
 
Solution
As above, it depends upon your expectations of performance of the graphics card. The GTX 1080 will have superior performance over the GTX 1070. Both are powerful graphics cards. An advantage of the GTX 1080 is that is can support higher FPS. That is important in preventing stutter and lag in the your display.

Both graphics cards have enough performance for 144 (+) Hz monitors as well as 2K and 4K. The balance will shift to the GTX 1080 for multiple 2K or 4K monitors.
 

Dugimodo

Distinguished
I would also add the 1070ti makes more sense than the 1080 unless the price is almost the same. Normally it's much cheaper and almost as good, it really depends on relative prices but I think it's the best bang for buck option if you want to do a bit better than the 1070 which is also a great card.