Solved Weird screen flickers and mouse lags on second monitor

Hello everyone,

I'm gonna go on a limb here and post about the weird issue I've been experiencing with WIndows 11. I have two monitors (1440p and 1080p), both running at 165 Hz. When my second monitor isn't focused, there's some weird flickering happening combined with some mouse lag. Here's a link of a 4K video @ 60 FPS. If the fullscreen app in the background looses focus, the flickering occurs along the mouse lag. But if I click on the flickering monitor, it all stops. Until I focus another window. I don't know if it makes sense and hope the video can explain what I mean. I tried turning off every programs and apps running in the background but it still happens.

Best regards, Drummer611.

Hey, @Drummer611, and welcome to the Windows Eleven Forum (aka 11F).

Looking at your video, it looks like the flickering is associated with the backlight, but the fact that it only does it when you are focused on a program on the other monitor is disconcerting.

Have you tried swapping the cables for the monitors (temporarily) to see if it is the cables / video port on your 4070?

Hey @johnlgalt, thanks for the welcome and your reply.

Actually I just did interchange my monitor's DisplayPorts to one another and the issue still occurs. What is odd tho is that the flickering only occurs on my second monitor. Never does on my main.

Hmmm. All settings for the monitor in question in Windows 11 Settings (Settings --> System --> Display --> Advanced display) seem correct? Refresh rate, and under the previous section (Settings --> System --> Display) the resolution?

Also, does the second monitor use a normal power cable, or does it have a power brick, similar to laptops, to power it?

Also, do you have HDR enabled for the second monitor?

Yes, both monitors are running at their native resolution and 165 Hz. (Although my LG is at 164.9 Hz but I doubt that would be the issue). Both monitors are using power bricks.

Hmmm. Yeah, the 164.9 won't make a difference, my own 4Ks run at 143.98, too.

If you have a multimeter, you could check the power output of the brick for the ASUS 1080p, but I suspect that something else is in play. What's really interesting is that ASUS specifically mentions that this is a flicker free monitor when running at native 165 Hz.

How about in nVidia control panel, anything weird in there when looking at Display --> Change resolution? And, for that matter, have you tried reducing the refresh rat for just the ASUS to see if it goes away?

I realize I'm spitballing at this moment, but I'm trying my best to rule out everything else before giving a prognosis that I really don't want to give - that the monitor itself is to blame.

Oodly enough, I change the refresh rate of my second monitor, I went all the way down to 60 Hz and it stopped. I raised it back to 165 Hz and it's not flickering anymore. I don't get it lol.

Keep an eye on it, it might return, but yeah, Windows sometimes forgets the settings it is using (or, rather, supposed to be using), and ever since I got my Eve Spectrums I've had to endure a whole new set of idiosyncrasies with Windows lol.

But for the nonce, glad it's finally gone. That backlight flickering would have driven me insane, having seen it in my Spectrums for one of the firmware updates for a while.

Yeah I'll keep an eye out. It will probably come back once I reboot my PC. At that point I guess Windows is to blame.

Thanks for your time .

Either that, or after going into sleep mode or the monitor itself being power cycled.

But at least it has stopped for now!

I did some Googling again and found out that this issue can happen when G-Sync is enabled. I had it enabled on my second monitor somehow, I don't play video games on that monitor anymore since my main is better.

That was going to be my next point lol - I figured that the refresh change fixing it, at least temporarily, was good enough for now.

My Eve Spectrums were playing hell with G-Sync enabled for a while, but the most recent firmware releases have all but fixed most of the issues that people were experiencing. Well, that and me not using HDMI anymore - both of my active monitors are now on DP and quite a lot has improved since I got off the HDMI 2.1 bandwagon.

Not something you can do, though, your ASUS is listed as having only HDMI and DVI, IIRC.

Actually my Asus monitor is DP1.2, HDMI and Dual-Link DVI. It's not officially a G-Sync monitor tho. That might be why there's some issues. Anyway, thanks for your help! I really appreciate it.

Odd, when I looked it up it said only HDMI and DVI. I must not have gone to ASUS' official website lol. My bad.

But yeah, G-Sync on an unsupported monitor is flaky for sure (heck, even on supported monitors it can be flaky lol).

And you're very welcome - glad you have a plan now moving forward to tackle this if it arises again.