high sierra 10.13.4 and 4k monitor refresh rate

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Level 1

16 points

high sierra 10.13.4 and 4k monitor refresh rate

I have a 2016 15" mackBook pro which is connected to an Asus 4k monitor through a Lenovo thunderbolt 3 dock. Up until last friday, the 4k monitor was working flawlessly at 3840 x 2160 60Hz. After upgrading to macOs 10.13.4, I'm having some issues:

the monitor now only works at 3840 x 2160 30 Hz which is kind of annoying
upon first boot the monitor is not recognised as "HDPI" and I need to turn it off/on to have it recognised as a retina display
in system properties, the monitor is identified as 5k/UHD+ display while it is indeed just a regular 4k monitor.

I have already reset SMC and NVRAM, but nothing changed. The monitor is using display port connection and it is set to DP 1.2 (multi stream protocol). I tried different cables, but it really looks like a software problem.

Any idea or suggestion ?

MacBook Pro (15-inch, Late 2016), macOS High Sierra (10.13.4)

Posted on Apr 4, 2018 6:45 AM

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Answer 1

Top-ranking reply

19936382383483

Level 1

4 points

Apr 18, 2018 3:42 PM in response to enryfox

I found what may be a solution, or at least what is working for me now. Screenshots attached.

When viewing System Preferences > Monitors and looking at the info pane for the external display, I was only seeing annoying cartoony "Apple for dumb people" icons for resolution - larger text, smaller text, etc. If you hold the Option key down while clicking the "Scaled" radio button, you'll get real resolutions. Then, if you check the box that says "Show low resolution modes" you'll get both a dropdown for all available resolutions as well as the available refresh rates for each resolution (even ones that aren't low resolution). I was able to select 4k at 60Hz.

Can anyone else confirm this works / helps?

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Answer 2

chuck_3rd

Community Specialist

Apr 4, 2018 7:10 PM in response to enryfox

Hello enryfox,

Thank you for using Apple Support Communities! I understand that you are experiencing some issues with an external display connected to your MacBook Pro. I would be happy to help provide some steps to take next. The first step would be to see if you can replicate this behavior in safe mode:

Use safe mode to isolate issues with your Mac - Apple Support

Testing the issue in another user is also helpful to isolating possible settings or software related causes:

How to test an issue in another user account on your Mac - Apple Support

The following support article contains additional troubleshooting steps to try for this issue:

Get help with video issues on external displays connected to your Mac - Apple Support

If you're still encountering the issues after, contact Apple via the link in this section:

Get more help

If you've tried these steps and your display still isn't working, contact Apple Support to get more help.

Cheers!

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Answer 3

enryfox Author

Level 1

16 points

Apr 5, 2018 11:45 PM in response to enryfox

I have done further tests :

my macbook pro with a different dock station (kensington)
another macbook pro just updated to 10.13.4

in all cases 4k resolution is stuck to 30 Hz. It is definitely a software problem, judging by all other reported issues regarding screen mirroring and external display it seems 10.13.4 really broke external monitor handling.

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Answer 4

DonH49

Level 6

16,716 points

Apr 5, 2018 5:06 PM in response to gsalfredo

have you zapped the pram?

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Answer 5

Apr 17, 2018 5:52 PM in response to chuck_3rd

I am also having this same issue - cannot display any content to an external 4k monitor because the display settings are stuck at 30Hz and the display requires 50Hz. Was working fine on OS 10.13.3 but is broken after update to 10.13.4. HELP!

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Answer 6

Apr 5, 2018 5:13 PM in response to DonH49

Yes, and as expected nothing changed 🙂

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Answer 7

MacOslo

Level 1

4 points

Apr 9, 2018 8:56 AM in response to enryfox

Updated on Friday. Asus 4K connected via UBC-C/Thunderbolt connection went completely black.

(Late 2017 MacBook Pro)

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Answer 8

Apr 18, 2018 4:14 PM in response to 19936382383483

That's a great find!

Didn't help me sadly, with the dock for every resolution option the refresh rate option is greyed out

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Answer 9

Apr 5, 2018 5:04 PM in response to enryfox

I have the same issue. Dell P2415Q 4K monitor attached via Lenovo Thunderbolt 3 dock. Running MacOS 10.13.3 all was well as soon as I upgrade to 10.13.4 I'm stuck at 30hz

Displays:

DELL P2415Q:

Resolution: 3840 x 2160 (2160p 4K UHD - Ultra High Definition)

UI Looks like: 1920 x 1080 @ 30 Hz

Persists through restarts, multiple users, OS re-install.

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high sierra 10.13.4 and 4k monitor refresh rate

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