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

For USB-C DisplayPort and ThunderBolt cables, there is too much signal loss and you MUST adhere to shorter than ONE meter standard. Data rates on todays displays are the highest and most unrelenting of any signals you Mac puts out, even fair than drive data.

DIRECT HDMI cables (not adapters) are using a somewhat different signaling technique. In the case of HDMI 2.0 cables for up to and including 4K at 60 Hz, you get much more latitude on length, but Certified cables of Ultra class are required. For HDMI 2.1, above 4K at 60Hz, that older HDMI signaling technique 'runs out of gas' and HDMI reverts to the same signaling technique as DisplayPort. At those speeds, you need a better cable, and it might need to be shorter as well.

Same thing happening to me. I have 2 Macbooks and 2 Monitors.

Macbook Pro 13inch M2 + dahua monitor (works 2K@165Hz)

Macbook Pro 13inch M2 + Samsung Odyssey G5 (works 2K@144Hz)

Macbook Pro 14inch M3 Max + dahua monitor (works 2k@165Hz)

Macbook Pro 14inch M3 Max + Samsung Odyssey G5 (display not detecting)

Using the same cable (USB C - DP) for all combinations above.

is the cable you are using shorter than 1 meter from the computer-end to the conversion electronics (often in the distal end) ??

is it also shorter than 1 meter from the conversion electronics to the display?

is the converter rated for resolutions this high? not all of them are.

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.

<< [it stops working properly] ...each time I play around with either the cable, or move the monitor a bit. >>

That is a sign of a damaged or imperfect cable or display, likely with a loose connection somewhere.

That is a sign of a damaged or imperfect cable or display, likely with a loose connection somewhere.

First I thought the same but the new cable works flawlessly with the M1s... So neither the display nor the cable is faulty. it's weird, but it seems it's how M3 handles the display.

Like I said, maybe a conversion cable is not a good idea after all. That's why I ordered a dock and use a native DP cable. I'll keep posted.

Recent Macs and recent MacOS have tightened the requirement that your connection be completely error free, or no connection will be made.

cables that 'shipped in the box' are notorious for being "lowest bidder" cables, and are typically only good enough to keep you from sending the product back to the store TODAY.

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.

Nov 2024 and this is still an issues. Also, I have an M1 and it is happening to my macbook as well. They have had a couple years now to fix this issue, and it is still a problem. Shouldn't have laid off all those people I guess.

I wouldn't have posted here that my problem still persists if any of these solutions would have worked.

Also, the fact that I found this whole thread, means readers (like me) are still finding these posts.

Starting a new discussion on the same topic is only going to make it much harder for future people to find the proper solution. Having multiple threads on the same topic only leads people to threads that do not show any solution (yet) and confuses people on which one could be holding a solution for them.

the ad shows 1 meter and two meter cables. which is yours?

Lapitco

what display are you connecting with this USB-C to displayPort cable?

Okay got it thanks, and just to clarify when you say under 1M, is that less than or equal to or strictly less than 1M?