Black screen for a few seconds after exiting fullscreen

Graphics / Linux Linux
1

Im not sure where to go with this issue. Or what is causing it, but I think its either KDE or an Nvidia problem. The problem started around Christmas, when VRR and new drivers and all that came out. I saw another user also had this issue around that time in discord chat for CachyOs.

I have an Nvidia RTX 4090, and 2x 4k screens.

The monitor im using is an PG42UQ, and it`s 120hz by default. It supports an OC that makes the screen go up to 138hz.

When I activate the 138hz, all fullscreen aplications makes the screen turn black for 2-4 seconds after exiting fullscreen. Then it comes back again. Like if I close youtube in fullscreen is an example to it. This is to everything that has an fullscreen.

This issue is not there, if I put my screen on 120hz automatic adaptive sync.

I tested 2 browsers, Brave and Firefox. Same issue on both.

But if I turn off adaptive sync to never on 138hz, the black screen goes away.

If I swap between 120hz and 138hz, my system hard crashes, so I need to push the reset button and reboot.

For me, its like it struggle to detect my hz in a way. After swapping to 120hz, it also detect my screen as an ultrawide, so i need to change it too 16:9.

Been so many major update past months, that I cant pinpoint what is causing the issue.

Had a new hard crash. So tried logging that as well under the nvidia-bug.report1.log.gz
nvidia-bug-report.log.gz (1.4 MB)


nvidia-bug-report1.log.gz (827.6 KB)

I see more people struggle with this for some reason now in the community. I linked my post and some people comming forward with the same issues.

1 Like
2

links to discord posts and nvidia-bug-report.log.gz would definitely increase chances of someone ever looking into this ;-) Cheers!

4

That 2-4 second blackout when exiting fullscreen on the PG42UQ (especially at 138Hz OC) is almost certainly a DSC (Display Stream Compression) handshake or a mode switch resync.

Since you are pushing 4K at 138Hz, the bandwidth requirement forces the GPU to use DSC. When you exit a fullscreen video (like YouTube), the browser or the compositor (KDE) might be flipping from a “Direct Scanout” mode back to the desktop composition mode. If there is even a slight mismatch in the refresh rate or color depth (e.g., 10-bit vs 8-bit) between the full-screen content and the desktop, the monitor has to drop the signal and handshake again.

To isolate if this is a video codec issue or a pure display signal issue, try this:

  1. Open a static, lightweight page like blacktestscreen.com or just a blank browser tab.

  2. Toggle fullscreen (F11) repeatedly.

If you still get the 2-4 second black screen on a static page, then it is 100% the monitor renegotiating the signal (likely VRR or DSC re-engaging). If it only happens with video content (YouTube/Twitch), then it is likely Firefox/Brave hardware acceleration conflicting with the Nvidia driver’s “Video Color Settings” or G-Sync windowed mode.

For now, sticking to 120Hz (native) usually avoids the DSC handshake delay on that specific Asus panel, as the bandwidth is lower.