MacBook Pro M4 with thunderbolt 5 and portable monitor

I just bought the new M4 pro with thunderbolt 5, but looks like it doesn't work with any portable monitors. I tried 3 of them using only one cable for both power and signal #portable. It only works if you power up the monitor then the power pass through it and then it can charge the laptop too.


Anyone experienced the same issue or if you have a similar setup can you check to see if is not just me? I also went to the Apple Store to check with a range of M* macs and looks like the only one with this issue is the M4pro w/ tb 5 (tested using both thunderbolt 4&5 cables)


I called the support but they just pass me around for 1h until they hang up eventually without saying goodbye :).


Just want to know if this is software fixable or a hardware issue as I do use this nomad setup quite often.


Thanks.



MacBook Pro 14″

Posted on Nov 14, 2024 07:35 AM

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Posted on Nov 19, 2024 11:54 AM

I already had that hub, I have 15 different thunderbolt cables of varying lengths, I have about 12 USB-C cables, capable of delivering display signals, also varying lengths, I have tested every single one of them and nothing works, and the one factor involved that seems to make the difference is that it is a thunderbolt five port.


every single one of my cables works with thunderbolt four on the M4 Mac mini. But again, as has been said, not a single of my 27 cables works when using the thunderbolt five ports on the M4 Pro Mac mini.


Thanks for your armchair input, but I think I will stick with hard results from my actual tests.


Though I cannot conclusively say that it is SPECIFICALLY because of thunderbolt five, I think we can all agree that something about the thunderbolt five models of the M4 Macs seem to have an issue connect connecting to portable displays and delivering signal.


Could this be a software issue? Maybe. maybe it’s a firmware thing that just needs an update. Could it be something else? Sure. But as of right now, based on every piece of evidence presented, it seems like Macs with thunderbolt five are not able to deliver a display signal along with the power to a portable display without that hub I am using or a similar one as the in between.


I get that in a perfect world, based on how things should be working in theory with thunderbolt five as you have explained in your other comments, it “shouldn’t” be an issue. But, here we are. 🤷‍♂️

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167 replies

Mar 29, 2025 08:06 PM in response to dragos-florin

I recently upgraded my Mac as well and was having the same issue. I have no clue what happened or what I did but both now are working and functioning with a single USB-C and no need for the mini HDMI. I just unplugged them and used it to game through my PS5. When I was done, I connected the one that was not working, and it finally came on. I said what the heck and decided to plug in the second one, and it came on with no issue. I work in IT, so this checks out as a fix haha, if you work in IT you'll get that joke. I honestly changed nothing and downloaded nothing. I wish I could say I did so I could help you all out but I have no clue what changed to make this work, and above is exactly what I did.

Nov 16, 2024 05:35 AM in response to dragos-florin

For sake of argument, have you taken your Mac to a Best Buy to see if any other monitors work better?

It could be there is a needed firmware update, or something has worn.


For sake of argument, have you made a copy of an older operating system to see if indeed it is the OS update which is incompatible as you claim?


You can use internet recovery to install an older OS on a separate partition of your Mac, the OS that shipped with the Mac.


Nov 16, 2024 09:06 AM in response to dragos-florin

Grant has a good point. The System Profiler makes it obvious why some of these issues exist.


USB/Thunderbolt is still serial. If you know anything about serially connected electronic devices they all work based on the weakest link of the chain. Have webcam in the mix? Its power will bring down the whole bus to the lowest power speed denominator. Have a USB-2 cable on one bus of the CPU, that's all the speed you'll get from the device. Wall powered hubs and docking stations help alleviate power drains on the built-in USB bus of the computer.


When Apple first adopted USB-C in 2016, I was stunned how a bus powered external hard drive was never seen through the hub, unless it had enough power passing through.


So dig through the profiler closely to see what's draining power and speed.

Nov 16, 2024 10:44 AM in response to Grant Bennet-Alder

Sorry for the confusion Grant, I seemed to have hijacked dragos's original post with my own different one.


I was just wondering why my M4 Pro Mac mini can't do what my M2 Pro Mac mini does, i.e. power the same 15 inch portable monitor on its own without requiring external power, I'm using the same cable on both. Could it be something to do with the Thunderbolt 5 port.

Nov 16, 2024 12:27 PM in response to Grant Bennet-Alder

Grant I recently purchased a MB Pro 16 M4 with a Max chip. I was under the belief that Thunderbolt 5 was a standard for this configuration. However, the hardware listed on the machine delivered shows all three ports as Thunderbolt 4. Went to Apple Store to look and all of their M4 Max and Pro units also showed Thunderbolt 4.


Have you seen this elsewhere? Has anyone purchased a machine that shows a Thunderbolt 5 in the hardware overview?


Please advise. Thank you.

Nov 16, 2024 02:17 PM in response to DougB851

https://www.tomsguide.com/computing/thunderbolt-5-vs-thunderbolt-4


The true lithmous is the amount of charge your Mac gets when hooked up with a 240W charger.


If they only get significantly less, then there is something to be said about that. Both Dell and HP have CAD/GIS laptops that uses two Thunderbolt ports together to achieve higher wattage. It sounds like from the spec, thunderbolt 5 seaks to offer that without the extra cable.

Nov 16, 2024 05:00 PM in response to dragos-florin

USB-C Power Delivery provides a mechanism to negotiate the delivery of power in either direction.


It doesn’t mandate that devices be willing to provide power, though. It only provides a negotiation mechanism and a standard for power delivery for those that do want to provide it.


You seem to be confusing your desire to power a display off the MBP’s battery for a standards based mandate that the MBP must provide that power. And you keep refusing to help people with any specifics that might help someone to figure out what is the case.

Nov 17, 2024 07:14 AM in response to dragos-florin

dragos-florin wrote:

Both laptops offer or the monitor accepts at the highest ~ 12W/5A


That photo shows a voltage of 4.84V and a current of 2.48A for a power level of 12W.


That almost sounds like Power Delivery negotiations failed, and the monitor is trying to draw traditional 5V power on the assumption that the USB-C cable can support 5V @ 3A (15W).


(Note that USB-C Power Delivery requires the use of cables that have embedded chips to tell the two sides that it is safe to transmit >5V and >15W of power. If in the process of measuring power, you changed out a PD-complaint cable for non-PD-compliant cabling, that may have forced a fallback to traditional USB power that would prevent you from measuring what you were trying to measure.)


This StackExchange Electrical Engineering thread says that according to USB specifications, "the 5V is supposed to be +-5% under load, which translates to 4.75V to 5.25V." If that's true, the 4.84V is within normal variance for 5V power. But this doesn't sound like the "higher voltage" power that the monitor manual talks about in Chapter 3, or the "at least 15W power supply" that the monitor manual talks about in Chapter 6.

Nov 17, 2024 09:12 AM in response to dragos-florin

Computer problems often have MANY moving parts, and very, very, very, often the actual causes are things that were NOT on your original suspects list.


For example, many display problems today are caused by cables that are perfectly good, but are not up to a high enough standard to do the jobs they are being asked to do.


You keep telling readers you tried multiple displays and all must be unsupported and therefore Macs are defective.


But to help you, we need to be able to replicate at least the specs of what you are using, and make certain it is all reasonable and there are no obvious distractions provided by any assumption or experimental setup error or mistakes you might be making.


We keep asking you to please do your due diligence and report to us the EXACT experiment setup you are using, in complete detail, including:


• EXACTLY what make& model display you care about (so we can look up its specs and be certain it should be expected to work in these circumstances)


• EXACTLY what cables and adapters, including whether they are certified, or have Trademarks on them, and about HOW LONG they are. (Some are known to not be adequate.)


• EXACTLY what is connected to what, and if the problem persists after a Restart if you do not change ANY cables.

MacBook Pro M4 with thunderbolt 5 and portable monitor

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