Settings > Video > Output:
“Screen Resolution” and “Set Display-Reported Refresh Rate” seem to display the info about my main monitor even if that is not where Retroarch is currently on. For Example, my main Display is 1920x1200@60hz (as is monitor 2). Monitor 3 is my TV which is 3840x2160@120hz Nevertheless, it appears to be working correctly. Is there any reason for this? Seems like a bug. Thanks.
Additionally, this is also relevant to me:
I noticed that I lose gsync with VRR after I go to the menu a few times. I get a lot of tearing. The solution is to close RetroArch and start again.
I’m on an RTX 3070
Not a solution, but you will get much better performance if Retoarch is displaying on your main monitor. I would suggest making your TV the main display if at all possible.
It may solve the second issue as well.
Turns out the 2 are related. When I manually told retroarch my refresh rate is 120hz, that seemed to have fixed the issue. I also disabled vsync and enabled the vrr option. So far so good!
That said, I think the fact that it doesn’t detect the monitor you’re using is a problem. Soon more people will get their hands on the HDMI 2.1 cards and will likely experience my issue if left alone. My 2 cents.
Maybe, but since most performance guides for Retroarch insist that you manually set your refresh rate, maybe educating the user is more of a priority.
To solve the issue we would need a per monitor override so you could manually set the separate refresh rates.
TIL
I’ve only been using Retroarch for 5 years (anniversary was a few days ago! 
)
Guess you learn something new every day.