Apple M3 Pro, MacBook Pro - USB-C to DisplayPort not working

Hey, I have a 14" and a 16" M3 Pro MBP. Both were working fine with my Gigabyte G27QC monitor via USB-C to DP for the last week. I updated both to Sonoma 14.1.1 and now neither of them work with the monitor anymore. They don't even register it as connected. It works if I connect to the monitor via the HDMI port. Also, the USB-C to DP connection works with my old 2018 MBP and my friend's M1 MBA which has not yet updated to 14.1.1. Therefore, I suspect there is some issue with 14.1.1. I hope this is fixed quickly as it is very annoying.

Hi everyone,

I've also encountered the same issue and hope the following will help with troubleshooting tests - but note that none of these fixed my issues so concluding that there is a Hardware/Software specific issue.

My issue is with my MacBook Pro M3 Max (purchased in December 2023) when connecting to a Samsung Odyssey G85SB monitor via a USB-C to Mini Display Port purchased on Amazon. This setup initially worked flawlessly for about a week but then suddenly stopped. I'm unsure if this coincided with an OS update.

Troubleshooting Steps Taken (All using Sonoma 14.3 for all MacBook Pro's):

1. Monitor and Cable Check:

• • Tested the monitor and cable (USB-C > Mini DP) with a MacBook Pro M1 Max and two other MacBook Pro M3 models; all connected successfully.
  • Tested my MacBook Pro M3 Max on the same monitor model at Best Buy (thank you), indicating the issue is specific to my device.

2. MacBook Pro M3 Max Tests:

• • Attempted to force display recognition by holding the option key in display settings; no success.
  • General test of the USB-C ports - Connections using USB-C to USB-C and HDMI to HDMI worked normally.
  • USB-C ports functioned correctly with other devices like storage and scanners.

3. Operating System Investigation:

• • Performed a complete erase and clean install of Sonoma 14.3, including testing in Safe Mode; the issue persisted.
  • Restored my Time Machine backup on another MacBook Pro M3 (non-Max variant), and the display connection (USB-C > DP) worked, suggesting a hardware or model-specific software issue.

4. Hardware Assessment by Apple:

• • Sent my MacBook for repair; Apple replaced the Logic Board and Touch ID board, but the issue remained post-repair.
  • Finally today - received a brand-new replacement MacBook Pro M3 Max; encountered the same issue even before updating the OS, indicating the possibility of a M3 Pro Max model-specific problem.

Conclusion and Next Steps:

After extensive testing and interaction with Apple Support and seeing the other posts on this thread, it seems there might be a specific issue with the Sonoma OS and the MacBook Pro M3 Max model, as other M3 models function correctly.

If anyone from Apple Engineering sees this - I'm happy to work with you to troubleshoot this further or if anyone has any other ideas please reply.

Not the best way to spend the holidays!!

Yes, they are. I have a 3 foot cable as well as a few 6 feet cables that I have tried with. I've raised this issue with Apple and they have confirmed that it is a known issue with the new M3 machines. My case has been elevated to the engineering team.

Of note, I was also using a USB-C cable to transfer information from my old MBP to my new one. I had to use the migration assistant twice (I had to factory reset the new laptop for an unrelated issue). The first time I did the migration the new laptop was on Sonoma 14.1 and my USB-C cable was recognized as Thunderbolt (which it is not) and it did a wired transfer at ~1700 mb/s. When I did the exact same transfer later and the new machine was on 14.1.1, the cable was no longer recognized. I had to do the transfer via the P2P Wifi network which took much longer. It seems like this issue extends past USB-C to DP cables.

Regardless, Apple has confirmed that they have received other reports of this issue too and that they are working on it.

<<. This needs to be an option that can be turned off!! >>

The Apple standard for its built-in hardware-accelerated displays, makes them suitable for full-motion video for production/display of cinema-quality video with NO dropped frames, and NO dropouts or partial-blank scan lines due to memory under-runs or other issues. This requires a hardware rasterizer/display-generator for each fully-accelerated display. 

if you would like Apple to relax is standards and allow errors in transmission to the display, you should let them know on this page:

Product Feedback - Apple

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Same here, except M3 Pro chip. Macbook Pro 16" purchased on January 16 2024. Worked with external ASUS 4K monitor at home (USB-C to Display Port cable) and at work with 2 external displays via Dell docking station (USB-C). Currently only HDMI works. Macbook is charging fine via docking station, keyboard and mouse also works, just monitors don't work anymore. Sonoma 4.2.1, but I don't think it matters, the update was done a few days ago, monitors stopped working gradually, first HDMI via docking station gave up (I can still connect directly to Macbook and it works), then monitor at home and today second monitor connected to the docking station gave up. Obviously when I plug a Dell laptop all is fine, it looks like Macbook has problem with video via USB-C port.

Hi all,

I have a solution!!

I encountered this issue and while it may have been affected by a macOS update. I found a solution, all you need to do is purchase a USB-C to DisplayPort cable that supports 4k@144Hz 120Hz 60Hz, 2K@240Hz. I found this one https://www.amazon.com/dp/B0CJ8NQDFT?ref=ppx_yo2ov_dt_b_product_details&th=1 , which is currently 6ft and works just fine, so the comments about the 3ft cable may be true only under other circumstances.

I have a MacBook Pro 14in - M3 Pro chip.

I have a 28" , 4K monitor Samsung G70A Odyssey. I made sure my DisplayPort was configured to 1.4ver (though it supports 1.1 and 1.2). It has worked great so far, this cable does not output power via the usb-c obviously but it has been working great when used for external displays, even on clamshell mode. My monitor supports up to 144hz but the Mac with ProMotion obviously caps at 120, so that is the one I selected under the display refresh rate settings.

I knew this was related to a refresh rate cable limitation because it worked with my M1 MacBook Pro 13 (no ProMotion of course) with my previous display port to usb-c cable ( which only supported 4K @60hz ). To prove my point I was able to lower the built-in display refresh rate at 60 hz and it worked but only for a moment, maybe the Mac ports are designed to output the 60+ or more like 120 which would conflict with the cable limitations.

Anyway, hope this makes sense and helps everybody.

Thanks!

Later versions of MacOS are more closely enforcing a policy of "no transmission errors" and asking the display to report back any such errors on the EDID secondary channel.

When errors occur, recent MacOS either reduces the resolution or drops the display entirely.

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HDMI uses a separate clock signal in the cable (until you get to really high speeds when they switch it without changing the cables) HDMI cables perform differently from modern interfaces.

Than why it works for a few weeks with various monitors and cables, then suddenly it stops working? This theory smells like BS.

I've been in touch with the engineering team and have had a case open with them for a while now. They have let me know that this is not expected behavior and is a known issue. I even ordered a DisplayPort certified cable that was 3 feet long and I still had issues. It's weird because I have three different monitors I use with my M3 Pro MBP. A G27QC, CQ27G2, and a G27QPF. Using the same cable, it does not work with the G27QC, intermittently with the CQ27G2, and works perfectly fine with the G27QPF. There must be something with the monitor at play here as well.

This needs to be an option that can be turned off!! I am about ready to go back to a linux machine that I fully control. So tired of the dirty "planned obsolescence" tricks of Apple. "Error recognition" yeah right -- this is a monitor that worked PERFECTLY FINE with previous OS versions. There were no "errors". This is a made up excuse to drop older monitors. Apple should get sued.

Had the same issue. The USB-C to DisplayPort cable I had for my M2 MBAir, which worked great for the Air, just would not work for my new 14" MBPro w M3Pro chip. Tried all the ports and a bunch of settings. Am connecting to Samsung LC32F391FWN monitor (circa 2017).

All the comments and posts here were SUPER helpful in troubleshooting the issue, so I bought 2 new cables, one for the HDMI port, one for the DisplayPort. Both 6ft, both promote compatibility with Thunderbolt 3/4 and MBP M1/M2/M3. And I'm happy to report both work great!

• using default settings across the board (1920x1080 on both external displays) and 1512x982 on MBP

I now have 3 monitors - this 32" Samsung, a similar 27" Samsung, and the native display - working as planned!

Thanks for all the comments here in this community!

The cable is about 3 feet long. I also don’t understand why it matters so much that the cable is short if both machines were working properly with this exact setup exactly up until the update was performed.

The specs have been tightened, and some setups are no longer adequate.

More recent versions of MacOS appear to be more demanding that NO errors occur in transmission to the display. Cables that used to work may no longer work.

Thanks, caulbach, the information helped in fixing the issue with my extended displays 30" AOC gaming monitors. i am using the below configuration to make it work.

Apple M3 Pro.

2560X1440 both monitors supporting 120 Hertz.

using Plugable Thunderbolt™ and USB-C Dual Monitor Docking Station, 96W Lapt – Plugable Technologies \

this extender from 3yrs for previous version on M2 and now with m3 working perfect no issues.

they have latest version, but I don't need for now. Happy i am back online.

hope it helps,