Custom Resolutions on 2160p monitor

[acmilangr]

Hi all.
I am new on this forum, so nice to meet you.

I have a monitor ASUS MX27UC that is 2160p and i am happy with that.
I am using ASUS 1080ti GPU.

I am playing games on 60fps (usually) at 2160p resolution.

I have tried to OC my monitor and the maximum i get to work is 70hz.

The problem is that V-SYNC seems not to work correctly. i have tried for example on 62hz and i see something like stutterings or frame skipping on 62fps . it is actually bad on my eyes.
(i am testing on Battlefield and i see my fps (using Rivatuner) stucked at 62fps). At the options of the game it also recognise as 2160p/62hz the monitor.

So it seems that everything works perfect but it the result is bad.

The reason that i want to Overclock my monitor is to play games at 70fps (when the gpu can handle it). Also i have an idea to underclock at 54hz or 56hz for the same reason. So the games are smoother at 56fps/V-Sync.

Any help?