External Monitor Flickering via Thunderbolt.

Question

Level 1

18 points

External Monitor Flickering via Thunderbolt.

Hello,

I recently bought a M4 Pro MacBook Pro. When I connect it to an external display (Dell S2721QS) via Type-C to DP, the external monitor is flickering. Someone posted exactly the same issue on YouTube for a MacBook Air 3 years ago, but that solution doesn't help. Is there anyone who knows how to fix it?

Example problem

Some additional info:

I have work Windows 11 PC as well for work computer and it works fine I can get 4k HDR 60hz without any issue with the same cable.
I was using the same system with my old MacBook Pro (2016 Touch Bar) and no problem there as well.
If I use 30hz setting, flickering stops.
It is not happening always but it mostly happens especially when I watch videos. If I take off and put back the cable or turn on/off the monitor, it may help.
If I close the MacBook screen and use only external display, Flickering definitely happens with 60hz.
HDMI looks much more stable but I guess, it doesn't work when I close the MacBook screen. I would prefer to use type-c connection since I can use the same cable with my work PC.
Some fixes I tried:

Change the resolution
Change the refresh rates (The issue happens with 60hz)
Change color profile
HDR on/off
True Tone on/off
MacBook display resolution/color/refresh rate changes.
DDC/CI on/off
Night shift is off

MacBook Pro 14″, macOS 15.1

Posted on Nov 20, 2024 11:16 PM

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Answer 1

Nov 21, 2024 8:08 AM in response to Onste

"Works with Windows" says NOTHING about whether/how well its works with Mac. Windows has no standards of performance for displays. Set whatever resolution you want, and any problems under Windows are the Users' problems.

Older macOS is not as demanding about error-free transmission at the latest MacOS.

that display appears to be a 4K display capable of up to 60 Hzx without flickering, with:

HDMI

DisplayPort 1.2

DisplayPort 1.2 does not support resolutions as high as 4K at 60 Hz

<< HDMI looks much more stable but I guess, it doesn't work when I close the MacBook screen. I would prefer to use type-c connection since I can use the same cable with my work PC. >>

As long as the built-in display and the external display are not Mirrored, use with built-in display CLOSED should make No difference whatsoever.

I am not a fan of HDMI, but its use in this case Should be giving you better results, PROVIDED you are using certified cables at least as good a "Premium", and preferably "ULTRA" standard.

MacBook Pro models introduced in 2021 support HDMI 2.0 standard which includes 4K at 60.

MacBook Pro models introduced in 2023 support HDMI 2.10 standard which exceeds 4K at 60, but higher than 4K at 60 REQUIRES ULTRA cables.

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Answer 2

Onste Author

Level 1

18 points

Nov 21, 2024 11:34 PM in response to Grant Bennet-Alder

Hi, thanks for your reply.

The HDMI cable that came with the monitor works fine. I also found a workaround: I’m using a Type C adaptor (Dell DA310) and it’s stable now. I assume Mac sees the adaptor and not checks the rest of the connection.

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