https://bugs.freedesktop.org/show_bug.cgi?id=93826
--- Comment #59 from iuno@posteo.net --- (In reply to Eike from comment #56)
Sorry to correct you, but my monitor has not been faultier than any other MG279Q that was bought before 2017.
Mine is bought before 2017 and it ain't broken.
BTW I have tried the mclock increase before RMAing my monitor and it did not work at all.
Because raising the mclk only helps for the other problem with too low voltage resulting in flickering, not the broken image.
Please differentiate between the artifacts I described (left half of the screen is offset to the right, a vertical stripe that should be in the middle is displayed at the left side of the screen) and other artifacts which could in fact be caused by a low mclock or other problems.
I do differentiate but I have to admit that I didn't read the ROG thread and realise others had this problem on Windows. Also, I didn't say your monitor or others might not be broken, I just said that there certainly is a software problem.
I've had the exact same artefacts you had but never(!) on Windows, neither on Windows nor Linux using Intel GPU. So it's easy enough to reduce it to the free drivers. I asked for help and agd5f suggested to raise the display clock (inside the GPU). It solves the problem entirely for me and others (as seen above).
Don't get me wrong, I don't question your experiences and I believe you had the same problem on Windows and a new Monitor fixed it for you. But I don't think suggesting people to send back their hardware when there is a software problem to be fixed is the right way to handle this.
The described artifacts might be fixable by software (e.g. Windows with certain driver combinations does show these artifacts, but does not with others), but ARE CAUSED by the faulty MG279Q firmware.
I have to disagree when doing nothing(!) but raising the clock of the display engine inside the GPU resolves the problem. The clock is too low on default which results in wrong timings, that's all.
Also, yours is running at 139 Hz, which is not a supported mode at all nor is it meant to do that, so you might be bothered about it but you still have a problem. It should run at 144 and mine does on Windows, it does with Intel, it does with the dispclk fix.
I have not found any combination of OS and drivers that caused these problems on the fixed monitor, but found several on multiple "not fixed" MG279Qs in the past.
Now what I find interesting and what we should focus on imho is the question why a new firmware resolves the issue (partly). Maybe they changed the modes/timings resulting in different GPU behaviour.
Could you provide your EDID as I'm really wondering?
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@withoutaface: You have to rebuild your kernel. It is not hard to do but if you're not familiar with that, tell us which distribution you are using and someone might help you.