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

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!

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!

EDITED: 🤦‍♂️

Guys/Gilrs! Just to say, its working...

After I read all messages of this thread, I give a second chance. I un-managed all my Dell cables and connected one only cable (DP to MiniDP) from Dell (curiously thinner than others) to my USB-C -> miniDisplayPort Adapter. And connected flowlessly and at 120Hz.

And with this adaptor that even was only mention 4k 60HZ.

https://pt.aliexpress.com/item/1005001858199340.html

was:

Just to share my pain, my previous MacBook Pro 15 i7 from 2015 I even connected 3 monitors, 1 hdmi and 2 minidisplayport... yeah.

But until late 2022/23 I worked with my old MacBook Pro with a Dell 3440x1440 @ 120Hz monitor via mini display port. Neat.

Now with the this new MacBook Pro M3Pro it's a disappointment, I can only connect by hdmi, which on this monitor, only makes 50Hz... I've already tried some usbc adapters for minidisplayport and nothing. Not even image. Every other PC computers or old Macs work in this dell. Except this M3... so frustrating.

I just purchased a mac book pro M3 Max. Prior to that I had a M1, and with a good usb-c cable I was able to extend the desktop no problem with my Dell UltraSharp 38 inch monitor. In addition, Dell monitors have a very nice usb docking functionality (this is an older non TB model) which worked great, I could pass my USB connections from the monitor docking to M1.

Not so with the M3. I bought and tried several not inexpensive different cables. The best I could do if I rebooted my mac it was able to detect the monitor, but the minute I disconnected the cable and then re-plugging it would not work. Also the USB pass thru would not work..

What solved it for me finally was (unfortunately) having to buy a separate TB4 docking station (an extra $200). Ugh, oh well. At least it all works the way I like it. I bought this one: Plugable docking station (TB4) I can use the included USB-C / TB4 cable to connect my monitor to it's USB-C input.

One word of caution, with this docking station I heard noise from my speakers when moving screens around, it's not a great power supply. Plugging my laptop's included Apple charger solved that problem. Hope this helps someone. Not a great experience with my M3 Mac.

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.

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.

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!!

I have 14inch MBP M3MAX + Samsung 49 Odessey, and my USB-C to DisplayPort does not work for this combo (the cable is fine and works for MBP M1 + Samsung 49 Odessey). However, it works when I connect M3 + Odessey using a very basic HDMI-HDMI cable. I am using BetterDisplay to switch between the monitors, but I suppose it is not absolutely necessary. Hope you can get your problems solved from my experience.

high end display data rates use dual-rail logic and are approaching the maximum switching speeds of digital logic. USB cables for high-end displays need to be one meter or SHORTER.

Your first cable is two meters. Does not work reliably in later version of MacOS

Your second cable is one meter.

specs I found HERE say:

2560 by 1440 display

Connectivity

HDMI 2.0 x2,

Display port 1.2 x1 (capable for HDR)

DisplayPort 1.2 says No Display Stream Compression, so the raw bit rate can not be exceeded, and is limited to HBR2 at 17.28 g bits/sec, VERY close to the limits for USB at 20 G bits/sec, and requiring the interface to 'turn around' the inbound conductors and use all conductors momentarily for outbound transmission. that also causes additional switching noise on the cable.

Anything short of an excellent cable/adapter will fall apart at those speeds.

@nerukner-

2560 by 1440p displays at up to about 120 Hz fit inside the 20 G bits/sec requirement of USB-C 3.2. They use what is called HBR-2 which requires 17.28 G bits/sec.

That high speed requires a USB port that can 'turn around' the inbound data pathways and use them for outbound data part of every screen refresh, at least 60 times a second.

straight USB-C cables required are certified to at least USB-C SuperSpeed PLUS, and show this logo, and are one meter or shorter:

An adapter/cable to DisplayPort should have one meter or less before the bulge of the adapter circuitry.

at those data rates, you can't put hardly anything else on that cable except slow-speed devices.

I could not believe that something what worked fine and suddenly stopped to work is related to cable. My Macbook Pro 16" M3 refused to detect DP monitors after OS upgrade to Sonoma 14.3. I was very sceptical about posts pointing to cables (It worked previously, right? :-) ). However, I decided to risk $25 and buy a cable. I picked USB-C to DP 8k@60Hz, 4k@144Hz and guess what? It started to work. The only issue now is that my docking station is almost useless (I still have keyboard and mouse plus power going through the docking station, but video I had to plug in directly.)

Why the problem surfaced after OS upgrade beats me.

[Edited by Moderator]

Guys, it is NOT about the length. It is about quality of a cable. You have to check the supported frequencies of the cable (or bandwidth). Pick one supporting 4K@144Hz / 2K@240Hz and you can have it even 10' long. Tested. I could not believe either, because before OS upgrade it worked with older cable.

Does shorter cable work? Yes and No. Here is what happened.

Same problem with MBA M3 15".

I had an M1 MBA and M1 MBP flawlessly connecting to a Samsung LU28R55 4K 60Hz monitor via 6 ft long 4k@60 DP Cable (QGeeM USB-C to Display Port, Thunderbolt 3 compatible), but this MBA M3 won't do it, and won't recognize the display.

This monitor features one DP 1.2 and 2x HDMI 2.0

HDMIs are occupied and I wanted to use DP for mac for greater image quality.

I always use my macs in clamshell mode.

Initial Observation with M1s: while disconnecting this 2-year old 2 ft long DP cable with the previous M1's there was always some momentary flickering on the screen and I never minded as it never caused a permanent problem, just when unplugging, seemed normal.

After countless trials with the new MBA 15" M3 and the 2ft cable, it never worked, never had a single pixel, and the display never showed up in the system settings.

Reading here, I bought the shortest I could find, one of the listed ones in a previous reply here (Silkland USB-C to DisplayPort 8K60 - 3.3 ft), and it worked with a caveat, and maybe not as intended. Here is how it works:

First of all everytime I connect the new cable, my MBA consistently shows it in the display settings which is a good sign, but not everytime the display works. It tries to display, maybe for a moment of two, but then flickers and goes out. It's just the way it was flickering with my other cable with older M1s only when I was trying to unplug them.

However, moving the monitor or the cable drastically changes the situation, when I hook up my MBA to the monitor, it takes me 3-4 tries to permanently get the display working. Each time I play around with either the cable, or move the monitor a bit.

When I got the display working, it works like a charm until I unplug or touch the cable, move the monitor etc. No going off after a certain time by itself. Not a single flicker even after days of hooked up. It's like trying to start a manual transmission car without battery, by pushing it. You struggle to start it, but once it starts it's good.

It seems like, the M3 is extremely sensitive and has very high expectations about the signal and a little change in the signal (by touching/moving the cable for example) immediately leads to drop/lose the whole signal altogether. Someone in the previous replies wrote something about that and I think it's true. M1s didn't work that way. It used to flicker when I start messing with the cable but it was just flickering, I never lost the display completely and when I stopped moving the cables the flickering always went away.

My M1s and M3 are using the same OS version Sonoma 14.5 and as M1s don't have this issue, I believe it's not related to OS.

For me, it's clearly about how M3 handles and manages display signals, and it's different than M1.

As a result,

Yes, shorter cable definitely works, but may not work every time.

When I successfully hook up, it works, but when I disconnect (and go somewhere) it's unlikely that I can get the display working when it hook up on the first try, when I come back.

For this inconvenience, I ordered a caldigit docking station with HDMI and DP port out, and I'm planning to try my standard issue DP cable hoping to get more stable connection as there would be no conversion on cable, and eliminate the flickering altogether.

I'll let you know if it works or not. Until then, I'll keep fighting my way with this cable.