The 'bottleneck' would be the monitor.
What resolution is this for?
If this is just 1080p, it's pointless to go beyond 1070/1070ti.
A 1080ti won't do more than those 2 at that resolution - it's for 1440p and 4k.
An 1800x is just a higher binned 1700(x)... very little improvement there.