depends what monitor youre running,what game types you mainly play,what fps youre happy with at a minimum etc.
The 1080 is overkill for most peoples situations & not great value for money.
There will always be a bottleneck in some shape or form - be it monitor ,cpu or gpu - its impossible to build a perfectly balanced system imo.
Ive seen plain & genuine reports that a 67--k paired with a 1080 offers more fps than a 6500 which plainly means that the 6500 can be a bottleneck in some scenarios.
A performance crippling or heavily noticeable bottleck ? - no ,but plainly there are points where it can hold a 1080 back.