(PG34WCDM) White horizontal lines on ultrawide OLED with VRR

[PWN3D_]

Hello everyone,

I'm really struggling to understand with this one:

After some back and forth on the ASUS Rog forum (well a lot of "back and not mcuh "forth" actually) I still cannot figure out what is going on with this model of OLED monitor, the PG34WCDM,


To summarize the situation: I am experiencing unusual white/grey horizontal lines on my VRR-enabled monitor when there are significant fluctuations in FPS. This issue is known to occur on OLED monitors due to gamma flicker, which I have observed on this monitor as well as on an OLED PG27AQDM; however, the white lines are absent on the 27" model.

At the store where I purchased the monitor, we tested three different PCs with varying hardware and multiple units of the monitor (I'm currently on my fourth unit, some had stuck pixels), yet the technician and I are puzzled as to why all the units display these lines.

I've adjusted numerous settings on the panel, ensuring features like pixel cleaning and uniform brightness that could potentially modify the image are disabled for testing. I've also conducted tests with and without DSC, but the problem persists.

For testing purposes, I use the Smooth Frog and the Gsync Pendulum demo from Nvidia. The lines become highly visible when the FPS rapidly transitions in and out of the VRR range (40hz), especially when using the fps slider in the Smooth Frog demo, and they are even more pronounced when the monitor is set to its maximum refresh rate of 240hz. The lines are still present at 180hz but appear fainter/greyer, and this continues to a lesser extent at 144hz and lower.

Could anyone suggest what might be causing this? After four units, I doubt it's a problem with the units themselves. My suspicion leans towards firmware issues, but since I seem to be the only one reporting this and Asus has not been communicative, I'm uncertain.

I can't insert a youtube video for some reason but here is the link:
https://youtube.com/watch?v=ZuULpciM9II

[PWN3D_]

Sorry for the double post but maybe I this video I just made is better to see those lines?
As you can see on Smooth frog while the image is fix and by simply moving the fps in and out of the VRR range, i get thoses lines.

Also I'm on an 4090 and 5800X3D and even though this test is kind of extreme with fps going as low as 10 fps, I can see the regulary in games while entering menus for example.

https://youtu.be/v2fXPYDXk0k

[PWN3D_]

After a lot back and support without any definitive conclusion, I think that G-Sync on this monitor is just broken, despite being certified G-Sync compatible.

From my tests, it seems that those white lines appear when the monitor randomly jumps to 240Hz when the FPS fluctuates too much. I can reproduce it using Smooth Frog and while fluctuate the FPS slowly out of the VRR range, triggering LFC. I can also see those lines and occasional 240Hz jumps on the OSD while still within the VRR range (120-135fps).

This is the first time I've personally seen this, and it does not happen on a PG27AQDM.

Now I don't know what is going on with this particular monitor, if it's a general defect of those monitors or simply a software problem or if it could be Nvidia driver problem, but the Asus support is relatively quiet on the problem.

[PWN3D_]

I just realized that this thread might belong in the G-SYNC section rather than the OLED Displays section, as the issue is more to how G-SYNC is acting on that particular monitor.

Could a moderator move this topic over there if it seems appropriate? Thanks!

[Chief Blur Buster]

I'll keep permalinks in both. There is now one over there too. Certain VRR quirks are LCD specific and other quirks are OLED specific.

[b00t.t4]

Just wanted to let you know I have noticed this with my 3080Ti FE w/ MSI MAG 274QRF QD E2. Exact same type of issue, random flickering white lines from what I can tell is when VRR is changing rapidly in games.

I will try to test with the software you tested with in the upcoming week.

[Chief Blur Buster]

Just wanted to let you know I have noticed this with my 3080Ti FE w/ MSI MAG 274QRF QD E2. Exact same type of issue, random flickering white lines from what I can tell is when VRR is changing rapidly in games.

I will try to test with the software you tested with in the upcoming week.

That's interesting.

It could be a driver bug instead of a monitor bug if flickering white lines are occuring on completely different displays.

[PWN3D_]

Just wanted to let you know I have noticed this with my 3080Ti FE w/ MSI MAG 274QRF QD E2. Exact same type of issue, random flickering white lines from what I can tell is when VRR is changing rapidly in games.

I will try to test with the software you tested with in the upcoming week.

That's interesting.

It could be a driver bug instead of a monitor bug if flickering white lines are occuring on completely different displays.

Hi Chief,

Thank you for the permalink of this thread!

I tested it a little more with a new firmware that was available not too long ago and same thing happens.

I also tested it today with an AMD RX550, and those exact same white lines appears... so I don't really know what is wrong with this model of monitors (as a reminder I've tested 4 of those, and have a few people reporting the same issue the ROG forum).

As an added bonus, here is test from PC Monitors on YouTube where he also encountered this issue, which initially misinterpreted as camera problem using the VRR Flicker Test to see gamma shift (Timecode : 44:40) : https://www.youtube.com/watch?v=EAs_MPXAvM4&t=2706s

[PWN3D_]

Update

After some back and forth with customer service here is the last anwser

"After internal confirmation, the issue you're experiencing is caused by the graphics card being unable to provide a stable output on the OLED panel.

Due to the varying brightness levels at different refresh rates on OLED panels, this leads to visible flickering. Currently, the manufacturing technology of OLED panels cannot compensate for the flickering caused by unstable graphics card output. This is a common issue with OLED displays across other brands as well.

To mitigate this, we recommend lowering certain settings in the game, such as texture details, animation effects, or turning off VRR (Variable Refresh Rate), which can help ensure stable output from the graphics card."

Thoughts? That would explain the gamma flicker that come with every OLED panel when using VRR, but to me that doesn't why the PG34WCDM comes with extra white horizontal lines on top of it.

I will probably try in the next couple of days the LG 34GS95QE that come with the same WOLED panel as this one and see if it has the same behaviour.

[b00t.t4]

I haven't had a chance to test yet, life got busy... Still getting the same behavior with white flickering lines in games. Even with latest NVIDIA drivers 572.16 and W11 24H2.

Strangely enough, I have started to get where the screen will even go black briefly for 1-2 seconds. It is rare, mostly just the white lines and flicker.

Need to get around to testing with the Smooth Frog.