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Comment by prussian | Hacker News Reader

I'm wondering if the real issue is the user doesn't have a DisplayPort 1.4 supporting cable or equipment. The speeds, color (10bit) and the resolution suggest to me that could be the real problem. I doubt the monitor would intentionally ship with such out of spec edid, especially since the monitor claims support from 48Hz to 144hz, likely for variable refresh rate.

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I was wondering that, too. I couldn't find the actual model of the monitor anywhere on the page. But LG has several monitors in its UltraGear line that do 3440x1440 at 144Hz: https://www.lg.com/us/gaming-monitors Presumably he's got one of them?

In that case it's not so much the EDID that's wrong but something else in his setup that won't work with those capabilities, and either Windows and Apple just don't default to maxing out the refresh rate, or they do but are able to detect that it's the wrong cable. Or it's a graphics driver issue?

Thought exactly the same.

I wouldn't be surprised if MacOS and Windows simply default to 60Hz unless manually selected otherwise, just to reduce customer service tickets.

Debugging this issue on linux is maybe an exciting journey, debugging it over the phone with a end-user who only has one cable and one monitor is just a PITA.

I'd consider it a Linux bug if the kernel drivers don't transparently hide high color depths and refresh rates that aren't supported by the display/cable/GPU's maximum supported DP data rate.

DisplayPort cables don't have identification chips inside them. The only way for the machine to know if the cable is capable of running at DP1.4 speed is to try to bring up the link at that speed. The software does correctly hide modes that the endpoints say they cannot support, though that won't help when one endpoint lies.

I saw this was noted online as a potential issue so I did try two different cables first and neither of them worked. It's completely possible that neither of those cables were up to spec either, so I've ordered one that is VESA Certified to support DisplayPort 1.4 and I'll have to check and see if they work without the hack when they come in. I'm on my Mac now and it just lists 85 and 50 Hz in the display settings which seems odd.

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