MacBook Pro M4 with thunderbolt 5 and portable monitor

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.

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.

You have nothing that requires or can use Thunderbolt anything, and certainly not Thunderbolt-5. You paid dearly for that ThunderBolt-5 cable, and it seems to be a complete distraction in every way.

I recommend you try using a simple USB-C cable one meter or shorter, and see if that allows it to run the way you expect.

ToddGeorgeKelly wrote:

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.

The M4 Pro Mac mini is a different machine than the "MacBook Pro M4 with Thunderbolt 5" that the OP has. (Assuming that the OP is correct about having TB 5, that implies that the MBP has a M4 Pro or Max chip; one which had a plain M4 chip would only have TB 4.)

In the OP's case, it looks like the portable monitor works fine with the new MBP – as long as it is given its own separate power source, as the monitor manual recommends. The last set of power measurements show that monitor drawing an enormous amount of power (50W) from an external power bank, relative to specifications claiming that it uses 17W, and a manual saying that a 15W power source would be sufficient.

I don't know what monitor you are using, or what its manuals say, but I suspect that the M4 Pro Mac mini is not designed to offer huge amounts of power to external devices.

For that matter, I doubt if the plain M4 Mac mini is intended to supply 50W of power to external devices. Maybe the two have the same power supply, and you just got lucky with the plain M4 Mac mini because it did not need quite as much of the power from its own supply to run its own internal circuits.

I just had a web chat with apple and I asked the question, why does my portable monitor and cable work with M2 pro and not M4 pro, and this is what they said:

Apple

Okay, can you check if the cables that you are using support thunderbolt 5 connection?

Me

I very much doubt it. Both came with the monitor. Do I need specific thunderbolt 5 cables

Apple

Yes, can you try checking on the website for the manufacturer for the displays to check the type of connection the cables support.

Me

Could I just confirm something please. Are you saying that because I am trying to connect to the thunderbolt 5 port on the M4 Pro, I need to upgrade my cables

Can I rephrase

Does the thunderbolt  5 port require different cables to the M4 and M2 pro Mac minis

Apple

Yes, I am asking you to check the compatibility of the displays and the cables that you are using.

There are different type of thunderbolt connections used on old and new Mac mini computers

Me

So the new thunderbolt 5 port is not backwards compatible with my old cables

Apple

First you need to check if the displays that you are using support thunderbolt 5 cables

If they do, then you need to get thunderbolt 5 cable to connect the displays

The new type of cables with thunderbolt 5 will also support the old type of thunderbolt connections

I have 14" M4 MacBook Pro with the M4 Pro chip (14 core CPU/20 core GPU). As per attached screen shot the system info shows it as havingThunderbolt/USB 4. Why does it not say Thunderbolt/USB 5? I note that the speed is listed as up to 120 Gb/s.

Did you ever get to the bottom of this? I was about to buy a Thunderbolt monitor with the intention to use it with my new M4 Pro MacBook Pro. I like the idea of no power cables and plugging the monitor directly into the MacBook Pro with the appropriate Thunderbolt cable. But now I am hesitant.

I really hope you get some resolution to this important question. I’d appreciate if you keep us informed as I’m very actively looking for a thunderbolt monitor, but if I have to buy one that requires its own independent source of power beyond my M4 MacBook Pro, then that factor will certainly influence my decision.

Same problem with an MNN portable monitor.

I have an older MacBook Pro from 2019. I used the specific Apple branded Thunderbolt 5 cable I bought with my new MR Pro to connect to my portable monitor. Works fine. So the cable is fine and backward compatible.

Apparently, my monitor doesn't support Thunderbolt 5.

But here's the goofy part that makes no sense. I connected my M4 Pro to the same monitor using an HDMI cable. Nothing.

So, now I think it's the chip or some OS setting.

Maddening!

How is it possible that this isn't a a massive issue at Apple right now requiring an emergency upgrade?

HDMI cable does not carry power in either direction. Just signal.

if it's a high resolution display, the HDMI cable spec becomes important as well. Best results under 4K at 60 requires "PREMIUM" HDMI cables.

This is close to showing it's not just you.

MacbookPro 2019 USB-C

Portable monitor with no external power--just plugged into the MB port

Using USB-C Cable. Perfect

Using cable that came with monitor. Perfect

Using the NEW APPLE BRANDED TB5 CABLE. Perfect.

New MacBook Pro M4 Pro

Portable monitor with no external power--just plugged into the MB port

Using USB-C Cable. No signal

Using cable that came with monitor. No signal

Using the NEW APPLE BRANDED TB5 CABLE. No signal

Longtimeusers1014--

the appropriate response in that case is to ask the display maker why a known-good sample of their product does not work with the latest MacBook Pro M4 PRO. The manufacturer has the Engineering expertise to find out why, and if it turns out to be a computer problem, to pressure Apple to fix it.

You will, of course, need to provide enough information about your setup so that they can duplicate and instrument that system in their lab.

Were you using BOTH displays as Hardware-accelerated displays? or was one or the other a DisplayLink or other type of "fake" display?

Did you install the same Driver software you had on the other machine or previous version of macOS?

I think I know the answer.

I just heard back the from the support people at MNN, which makes the portable monitor that I have been using successfully without an auxiliary adapter power on my 2019 MacBookPro with Thunderbolt 3 ports and yet cannot make work on my brand spanking new MacBookPro M4 Pro Thunderbolt 5 machine.

I asked point blank this question: Does your monitor work with Thunderbolt 5 ports using only one USB-C or Thunderbolt cable and no auxiliary power adapter?

Answer: No. The monitor is not compatible with TB5 ports. It will need an auxiliary power source (adapter) and also an HDMI cable. And even when using the auxiliary power adapter the monitor won't recognize a signal through its USB-C ports if the signal is coming from a Thunderbolt 5 port.

And so now I am using the power adaptor that came with the monitor, an HDMI cable going from the MB M4 TB5 port to the monitor, and everything is working. But obviously, this defeats the whole purpose of a portable monitor.

And so folks, it looks like we will need to wait for the portable monitor manufacturers to start making portable monitors that work with Thunderbolt 5 ports.

Maddening and super disappointing. Especially since you can't even know whether a new monitor will work because the specs don't address this issue.