Depends on how much RAM you have which will determine the bottleneck. I'm kinda tired of these posts. They are lame, uninformed and useless. With a modern processor you will almost never have enough of a bottleneck to worry about. Ever. Period. End of story.
Absolutely not, i have them both currently, 4.4 6600k and g1 1070, gpu load doesnt go below 95% even in the heaviest of games and sometimes with some gpu oc i add, results remain
my i5 3470 is still dam good only like 10 - 15 % slower and i notice game reviews my cpu still holds on top with only 3 fps slower vs most top end cpu's