frostmouth2 :
geofelt :
Not a problem.
Your monitor is limited to a 60hz refresh rate, it is likely that your GTX1080ti will be capable of generating frames faster than the monitor can handle.
Nvidia drivers have adaptive vsync which is a buffering technique to handle such mismatches to avoid screen tearing and reduce input lag.
Hmm. So its Ok to get a AMD Freesync 4k monitor with High-End Nvidia cards to play at 60 Hz. Is that what you mean?
What do you think about CB281Hk?
That monitor looks very much like the LG 27MU58 that I have on one of my pc's
https://www.newegg.com/Product/Product.aspx?Item=0JC-000D-005B0
It runs 4k resolution just fine with a GTX750ti at 60hz. It is a freesync monitor.
I do not run fast action games, but those monitors seem perfectly capable of doing so.
I don't know what to think about the two you listed.
If you can, go see the monitor candidates in person.
Otherwise, look for reviews.