Reddit failed me so here I am.
This has me stumped. My Acer xf270hua makes a constant, very high pitched noise when I turn on my pc and doesn't go away, but if I turn the monitor off and on again it goes away instantly. Sometimes it comes back after my monitor being on for 12 hours, but once again turning it off and on fixes it. I don't think it's coil whine. My main Acer monitor will be referred to as monitor 1 and my second 1080p Asus monitor is monitor 2.
Now for why I find it pretty weird. First of all, when I turn off monitor 1 nothing changes on my second display, but when I turn it back on monitor 2 quickly turns off and on, and all my windows appear on monitor 1 as though Windows very temporarily set monitor 1 as my main and only display. As far as I know, simply turning off the screen doesn't mess with display properties in windows?
Second, this has only appeared recently after I changed the refresh rate of my monitors. I recently realised that because I'm running two 144hz monitors my graphics card never downlocked, which I was able to fix by running both my displays in windows at 120hz instead. I started to notice the really high pitched noise so I changed my main monitor back to 144hz which made the noise go away, so I figured I'd fixed it. However, it comes back every time I turn on my PC. My cards are both now running at 120hz since this allows my graphics card to run as low as 139MHz instead of a constant 1500MHz or so at idle.
I'm just wondering if anyone has any idea what it could be causing this issue or how to fix it. It's not the end of the world since I can turn off and on my monitor every time I turn on my PC, but it's clearly indicative of something wrong and I'd rather not blow a capacitor or something, I really know nothing about monitors.
For system specs I have the acer xf270hua as my main display, asus vg248qe as my second display. Both connected to a 1080ti. I'm on Windows 10. Please does anyone know if this could be anything software related? It only started happening the moment I changed my monitor refresh rate so I'm still hopeful I won't have to try to get it replaced.