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macOS High Sierra (10.13.6) 4k at 120hz is it possible?

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Jul 2, 2014
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Motherboard
STRIX Z370-H GAMING
CPU
i7-8700k
Graphics
GTX 1080 Ti
Mac
  1. iMac
  2. MacBook Pro
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  1. Android
Hey,

For some reason I can't see any options to run my brand new Asus XG438Q at 4k above 60hz under High Sierra. It runs flawlessly under Win10 at 120hz. Is this problem tied with nvidia web driver or monitor support?

Is it even possible to run 4k more than 60hz with latest High Sierra web drivers? I haven't tried with any AMD card yet.

Thanks!
 
What options do you get in Display Preferences when you hold Alt/Option on your keyboard and click 'Scaled'? It should enable more options for you and possibly a dropdown for enabling 120Hz. If that doesn't help, then try downloading the latest version of SwitchResX (latest beta link) to enable more compatible resolutions, including high refresh rates.

Although I'm not using an NVIDIA GPU or High Sierra, I actually experienced the same problem and finally fixed it today with joevt's help. I have an Acer Nitro XV273KP (4K 120Hz, DisplayPort 1.4) that I was having trouble running at scaled 2560x1440 HiDPI mode in 120Hz. The latest beta version of SwitchResX was the key to getting it working properly.
 
Hey, thanks for quick reply.. I've tried the alt/option part.. that only shows 60hz option as well (It might somehow be connected to the reason that MacOS seems to call my monster monitor "a TV")

I also installed SwitchResX (not beta tho) and tried to add manually a custom resolution with 120hz (same settings that are set under windows, nvidia control panel) but for some reason I couldn't add that resolution (with message Not activated - invalid?)

I'm not at home currently, so I can't try out the beta right now.. but did it just have the 120hz option available out of the box, or did you have to add a custom one yourself, also do you run High Sierra, Mojave or Catalina?

PS! I'm running the original DP cable what came with the monitor - works fine under windows
 
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I also installed SwitchResX (not beta tho) and tried to add manually a custom resolution with 120hz (same settings that are set under windows, nvidia control panel) but for some reason I couldn't add that resolution (with message Not activated - invalid?)

You have to run the beta version for now because it includes specific fixes for high refresh rates on 4K+ monitors. My panel is basically the 27" version of yours.

Are you just trying to run native 3840x2160 resolution at 120Hz without any scaling? The 120Hz option should be auto-detected in SwitchResX 'Current Resolutions' tab. If you have the beta version I linked above, then it should show all the high refresh rate options.
 
You have to run the beta version for now because it includes specific fixes for high refresh rates on 4K+ monitors. My panel is basically the 27" version of yours.

Are you just trying to run native 3840x2160 resolution at 120Hz without any scaling? The 120Hz option should be auto-detected in SwitchResX 'Current Resolutions' tab. If you have the beta version I linked above, then it should show all the high refresh rate options.

Just installed the "Beta" Version (4.9.1a2) but still not 120hz Native resolution options under "Current Resolutions", did "Restore factory settings" and restart but that didn't help either.

Screen Shot 2019-09-02 at 17.04.18.png
 
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Did you try setting anything in the Display Information tab? Try entering 3840x2160 120Hz in the 'Startup Resolution' field and then restart and see if that helps.

Other than that, it's possible there's something about High Sierra that prevents it from working at the full refresh rate.

You could ask joevt if he has any clues about what's going on. I've been chatting with him in this thread:
 
Report the output of the following command:
Code:
/System/Library/Extensions/AppleGraphicsControl.kext/Contents/MacOS/AGDCDiagnose -a > AGDCDiagnose_a.txt 2>&1
This will verify if you have a proper DisplayPort 1.4 connection necessary for 4K120.

The new SwitchResX beta is only needed if you have more than 256 resolutions which may happen if you enable the new "All refresh rates" for scaled resolutions in Mojave (Mojave is not an option for Nvidia though).

You don't need that option for the native (non-scaled) resolutions of 4K120 or 1080p120 HiDPI. But you won't be able to use scaled resolutions like 1440p120 HiDPI in High Sierra (unless someone makes a patch to CoreDisplay/etc... for High Sierra).
 
thanks, joevt! Here's the report from AGDCDiagnose
The display reports that it supports HBR3 but it is only being set to HBR2. I don't know if that's a problem in the driver, or because you're using a 4K60 timing that does not require HBR3.

How exactly is the display connected to your computer (which ports and cables)?

In Windows, can you show a screenshot of the Advanced tab of GPU-Z while the display is running at 4K120? Do the same for 4K60.

Report output of "kextstat" command. This will list kexts to look at.

Perform "log stream" instructions at #813 - might give a clue why a timing is rejected. First, try it without a predicate (because we don't know what nvidia kexts are involved).

I'm sure that AMD cards support DisplayPort 1.4 in macOS (see #816). I need to find an example of someone getting HBR3 to work with Nvidia Pascal cards in macOS (earlier cards only support HBR2 I think).
 
Monitor is connected via DP cable (what came with the monitor) to 1080Ti.
Attached two screenshot (first 60hz, other 120hz from gpu-z), kextstat and logstream.

gpuz-4k60hz.png

GPU-z 60hz

gpuz-4k120hz.PNG

GPU-z 120hz
 

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