External Monitor flickering issue on M3 MacBook Pro

I recently bought an M3 MacBook pro 14" to use with my external monitor (Dell S2721QS) via a USB-C to Display port cable. This setup worked fine with my previous laptop, a 2019 Intel MacBook pro, and with the new one initially. However, after a software update (I dont remember which one, as I was travelling and not using the monitor at all at the time), I started to experience issues. Essentially what is happening is that whenever I plug the laptop into the monitor it works, but every few seconds the external display goes black for a few seconds, before continuing to function. It does this every 10-15 seconds, and is very annoying. I have tried using my family members MacBooks with the monitor, and my dads MacBook (M2 16" MacBook pro) has the same issue. However, my old intel mac still works fine. All of the macs I have tested are fully up to date (Sonoma 14.3.1) at the time of writing this.

[Re-Titled by Moderator]

MacBook Pro 14″, macOS 14.3

Posted on Feb 27, 2024 12:12 AM

Top-ranking reply

cougracer900

Level 1

14 points

Posted on Apr 2, 2024 10:26 AM

Update. Chatted with support and apparently the only fix if you want to use HDMI or Thunderbolt to HDMI you need to lower the refresh rate even if the monitor supports the higher rate. I moved mine from 60hz to 50hz and it resolved the issue. However if I ever want to stream 4K/1080P at 60hz I will have to manually change it back.

Apple needs to fix this issue because a monitor that supports 4k/1080P at 60hz should just work...especially since my old Macbook Air (2020 M1) had NO issues and worked fine with the same monitor at 60hx refresh rate.

I noticed the original post mentioned a Disply Port set up, I cannot speak to that option as I only have the HDMI and USB-C to HDMI set up.

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19 replies

noahandi1 Author

Level 1

22 points

Feb 27, 2024 2:19 AM in response to Luis Sequeira1

Yeah, I replaced the cable which didn't work, and have also tried an HDMI cable, and a USBC to HDMI. Both work, but not at 4k 60hz on the monitor, which is the reason I bought it.

Mar 6, 2024 7:04 PM in response to noahandi1

I'm having the same issue on my M3 MacBook. I bought a new HDMI cable and it's still happening. My monitor also doesn't flicker when plugged into other Macs or my PC.

Quiboloy

Level 1

8 points

Mar 12, 2024 12:39 PM in response to dafafadsfafasfdasfas

My external Dell Monitor with HDMI port issue M3 Mac Pro is flickering., How can I fix this

Apr 7, 2024 1:37 AM in response to generalstudies™

update: unfortunately direct to USB-C worked on the sites that had issues, but then after 30 min of use, I stumbled on another site and the flickering occur again :(

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External Monitor flickering issue on M3 MacBook Pro