144Hz refresh rate with 4K?

atanvarno

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I have latest Big Sur running on X570, with Sapphire RX 5500 XT card, with LG 27GN950 monitor. This hw works great in Win 10 with 144Hz 4K res, using DisplayPort 1.4 with DSC.
But in macOS, I can't get anything more than 95Hz to show up.

Is there a list of possible solutions to try out to get this fixed..? EDID hacks, WEG boot params etc..? I am willing to try just about anything to get this working. It should be working, hw is capable.
 

AudioGod

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Look into this and see if it’s affecting you,

Also check your DP Cable and if you have a second one lying around try it out.

I had exactly the same problem with my 4K 144Hz Monitor where it was fine under windows and unable to go above 60hz on macOS to fix it I bought a high quality VESA Certified DP Cable from Amazon and as soon as i swapped it over it I got full everything across windows, Linux and macOS.

Heres a link to the one I got.....

Cable Matters VESA Certified Braided DisplayPort 1.4 Cable Fully Support 8K HDR and DSC - 1.8m
by Cable Matters
Learn more: https://www.amazon.co.uk/dp/B0856Q7..._dp_P91QR45NZAWCRJ5ZVTWW?_encoding=UTF8&psc=1
 

atanvarno

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I have proper super-thick DP cable, to replace the original one that came with the monitor (which was too short). I specifically bought it to support for 4K 144Hz thus I don't think that's where the issue is.

EDID hacks like the one you linked might be the answer, will try to look into this. Not sure - was it possible to fake the EDID through OC's DeviceProperties section?
 

AudioGod

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Using big sur I doubt it very much. The method I sent you is easy to do as it’s done via a profile. You can’t get simpler then that really.
 

atanvarno

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I used SwitchResX to extract EDID info for the monitor. Here's an interesting part:

Code:
Display type:
-------------
    RGB 4:4:4 & YCrCb 4:4:4 & YCrCb 4:2:2 Color Encoding Formats
    Display is continuous frequency
    Default color space is not sRGB standard

Entire output is attached. It's late now but will try tomorrow to see if I can convince it to use 144Hz.
 

Attachments

  • 27GN950-EDID.txt
    11 KB · Views: 1

atanvarno

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I tried two scripts. The original linked from page you sent is a bit too restrictive - it removed all EDID extension blocks and only 60Hz was left.
I then tried this version which had no visible benefits but at least nothing was removed.
Thus my understanding is that macOS is already using proper color space with this monitor.

Mystery remains why is 120Hz or 144Hz missing. I did have 120Hz available in Catalina and in some weird cases 144Hz was also sometimes there but it was way too glitchy to be used properly.
 
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