My monitor is:Near as I know all 165Hz monitors are overclocks. I don't think anyone makes 165Hz panels. The make faster panels, but I've never seen a panel with that as its native rate. I wouldn't worry on it though, at those refresh rates you'd be very hard pressed to see a 21Hz difference. Even the difference between 144Hz and 240Hz is somewhat subtle (noticeable for sure, but subtle) so I wouldn't be concerned.
There is nothing in OSD about oc. I cant find. So anyway that issue is monitor related to 165hz only in 1080P?Well interesting, supposing the information I looked up is correct (and I can't be sure this isn't direct from Gigabyte) it uses an Innolux M270KCJ-K7B panel which IS native 165Hz, something I've never seen before. Another way to tell is if there is any kind of OC on/off thing in the monitor's OSD. In all the cases I've seen with OCable panels, you can turn it on or off in the monitor OSD. If it is on, the refresh rate shows up to the OS, if it is off it doesn't.
What GPU do you have and what kind of connection are you using? That sounds like a bandwidth issue to me, like the connection has the bandwidth for 2.5k @144 but not @165.There is nothing in OSD about oc. I cant find. So anyway that issue is monitor related to 165hz only in 1080P?