Im not sure where to go with this issue. Or what is causing it, but I think its a KDE problem. The problem started around Christmas, when VRR and new drivers and all that came out. Then i suspected it also could be Nvidia, but ive been testing different drivers, so Its the same. I saw another user also had this issue around that time im 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. 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 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.
Tried to upload some logs etc here. Its also reported on the nvidia forums with logs. Tried linking it here, but it does not seem to be happy with links
Hi - relevant sections of system logs could be posted here using the Preformatted text option within a post.
On the face of it, this sounds more likely to be some interaction between the NVIDIA drivers, your card and your monitor’s firmware, just based on cases like https://www.reddit.com/r/OLED_Gaming/comments/10icasm/pg42uq_unusable_in_overclock_mode/ , but seeing if there are errors in KWin or the kernel when that black screen happens might help guide troubleshooting.
I’m using 3 displays, 2 of them are 1080p and the problematic one is 2160p (4K), just like yours. Although mine goes to 160 Hz, and does not have an overclock mode.
Just like you said, the automatic adaptive sync detection seems to be part of the problem. If I set “Adaptive Sync” to “Automatic” in the display configuration, exiting fullscreen on that display by either:
Alt-tabbing
Pressing the meta key to bring up the application launcher
Moving the application to another display using Meta+Shift+Left/Right
Use the “Make Window Fullscreen” shortcut for KWin
all cause my screen to turn black for around 4 seconds, showing the “No Signal” screen.
If I set “Adaptive Sync” to “Never” or “Always”, the issue does not occur.
Since I run Arch, I experienced the recent problem with the kernel a week or so ago, and to work around it I temporarily switched to the Arch LTS kernel, but that also seems to have this problem so I would guess it’s not a kernel issue.
Yeah, I have been monitoring the Nvidia side of the forum as well. Seem that they have many cases of it over there as well. We have other Arch Linux user from CachyOs community with the same issue as well. I have not gotten any reply from Nvidia yet, if its driver related or a bug in KDE yet. So im standing by still
I have no idea how to troubleshoot things like this in Linux sadly.
I must admit that I have avoided bug reporting in Linux. Everywhere I come in as a normal user. Its like like I should know what the issue is before I report it, and know how to troubleshoot everything in my system. Where for me, its like… ok things are flickering on my taskbar, my screen goes black. I lose performance in games if i use color profile or color accuracy. I cant see anything if i use legacy scaling in the system on 4k. I know there is a major memory leak if you use a gif as a wallpaper in kde.
Most of the time, I have talked to a CachyOs dev about the issues in Kde. Then they pretty much patch on the fly if they find anything. They are pretty amazing But I dont want to bother em with it anymore.
Due Kde seems to have some issues here and there with stuff i mention up top.
Most of the time they have patched Kwin, like they know what it is from the time, explicit sync came on the table.
This still happen today, with flickering when we swap drivers from open and closed as well still.
From what Ive been monitoring on support side of things, most issues can be seen around 4k support and KDE. Usually same topic is around adaptive sync, color profile/color accuracy <–( Big performance issues while playing games, A1RM4X on youtube did put a video on youtube about the issue.) and the 4k support for scaling the desktop. If you come in with default kde legacy scaling now days. You cant see anything on the screen, due everything is so small that steam look like the size of my pinky finger. But swapping it to scaled by system, its pretty ok if you have a larger 42" screen, and you still dont see anything if you use a 27". KDE team need to upgrade to 4k screens and nvidia cards and test a bit how the experience is
Hey, for me (and I think most here) there’s no judgment for not coming in already knowing it all - nobody knows everything, and everyone has to start somewhere!
When I think of diagnosing a problem, I tend to go with:
What am I seeing, and what seems logically related? ex. my display is glitchy with weird artifacts - maybe my graphics card is loose, or there’s a driver bug?
When did I start seeing it? ex. if the issue happened after updating 10 software packages, it’s almost certainly connected to one or more of those 10 packages, so I can narrow down troubleshooting
What is the system telling me? ex. on an OS using systemd, what does the journal show at the time that I observed the issue? systemd/Journal - ArchWiki
Just a personal opinion - if you’re not sure that you want to get more practiced at troubleshooting, or investigating how and why your system is working the way it is, then Arch Linux-based systems might not be the best choice. The principles of the underlying distribution are to target users who are either already “proficient”, or are “willing to read the documentation, and solve their own problems”.
On top of that, CachyOS does things that, while possibly helpful in some cases, also give you a system configuration that’s less likely to have been tested by upstream developers in projects like KDE - so you’re more likely to be among the first encountering an issue, and in a position to put together an effective bug report so it can be diagnosed and hopefully solved for everyone.
Having said all that, if you’re struggling with steps to diagnose issues on your device with KDE software, or to create helpful bug reports, folks here will be glad to help point you in the right direction - just ask
I know you mentioned posting this in the NVIDIA forum as well, and I’d suspect that’s likely where the issue resides (or somewhere between the card and monitor). However, if it does seem like a KDE Plasma issue, then posting the system logs from when it happened - obtained using a command like sudo journalctl --since="2025-02-25 16:29:00" --until="2025-02-25 16:31:00", if the issue occurred at 4:30 PM - might be a helpful first step for folks to best guide you.
But I dont want to bother em with it anymore.