14 months ago
will an i5 have problems with a 1070
It all depends on what resolution and frame rate you desire and the application you are running. It also depends on which I5 you are talking about. If you mean coffee lake or newer for I5 then no the 1070 will be just fine.
what about this Intel - Core i7-6700K 4 GHz Quad-Core Processor
If you already have this CPU it will pair nicely with a 1070. If you don't already own it I suggest getting an I5-8600K. The I7-6700K is a couple years old but still very powerful but buying into an older platform for a fresh build is generally ill advised unless it is a killer deal.
Depeds on the i5. A 2400 might bottleneck a 1070 at FPS past 45, but a 7400 may bottleneck if in whatever game you are playing past 120 fps. A 6/7/8/9600k can easily render up to 165 FPS.