O,you cant run 4k with a GTX 1070,the GTX 1080 is better in every aspect but if you want 4k at very high settings or ultra you need 2x 1080's and that will cost a pretty penny,we really dont know why you need a Z170 Board if you dont plan on overclocking you said in your previous thread that you need the display ports,what for if you have a GTX 1070/1080