MacBook Pro M4 with thunderbolt 5 and portable monitor

I asked Plugable Technologies to test its USB-C portable monitor for laptop (USBC-PDMON) which has 2x 10Gbps USB-C ports for data or connecting peripherals, 100W PD pass-through (85W charging), 15.6” IPS display, cover/stand with a M4 Pro 14" MacBook Pro using one of the T5 ports. Looks like it works:

We've tested the USBC-PDMON with a MacBook Pro (14-inch, 2024, M4 Pro) and they worked well together. The portable monitor was able to successfully show video from the Mac, and the other functions such as the 10Gbps USB hub ports and Power Delivery pass-through also worked well.

Just passing that information on to those who are interested. Obviously contact the company to make certain before you buy it.

Sean1397,

Your guess is as good as our's. The first step is to contact AppleCare by phone or reach a genius bar or Authorized Apple Service Center and get a case #.

This is just a user to user forum with Apple moderation.

The number of times in 24 years I've seen Apple moderators actually say they are looking into a problem can fit on one hand.

This issue has been as much an issue with some older Apple displays as third party displays.

There are three places this can break:

1. The thunderbolt bus on the Mac and the kernel extensions addressing them, and any firmware speaking to it, and any differences in the kernel extensions of one operating system versus another. To isolate the operating system issue, downgrading is possible through steps listed on this tip. Energy Saver settings put hard drive to sleep can impact the USB and Thunderbolt bus on Macs, espceially when closing a laptop lid as the bus goes into low power mode. Once in low power mode only a fully powered laptop on restart with the display lid open will give you full power. This is even greater problem with displays powered by the Mac itself with no power of their own.

2.The use of less than optimal cables. Make sure you are using cables that least have the lightning bolt icon on the sheeth. Those without may be straight USB-C cables and those don't have as good a video signal carrier.

3.The thunderbolt bus on the display, and any firmware provided by the display manufacturer. Additionally displays with their own separate power source from the computer are less likely to be flakey with Energy Saver. Consult with the display manufacturer support if any firmware update is planned for supporting Thunderbolt 5.

Servant of Cat's wrote, "Please provide a link to the Technical Specifications which state that the M4 Max MacBook Pro will provide large amounts of power – in excess of the minimums for USB or Thunderbolt ports – to an accessory."

The Thunderbolt 5 specification requires that a port provide a minimum of 15W of power for accessories. https://www.thunderbolttechnology.net/sites/default/files/Thunderbolt_5_TechBrief_2023_09_12.pdf page 2.

Apple is advertising the ports on the Macbook Pro M4 as Thunderbolt 5 ports, as your post shows. Therefore, those ports are required by the Thunderbolt 5 specification to provide at least 15W of power for accessories. Ibid. But, available evidence suggests that the ports do not provide the required 15W of power.

My external monitors (Arzopa Z1FC) require a supply of 5v capable of 2.4A according to the manual. https://cdn.shopify.com/s/files/1/0570/9280/0675/files/Arzopa_Z1FC.pdf?v=1707041874 But, the ports on my Macbook Pro M4 Pro do not work with the monitors with a single cable (even with a USB SS20 cable which can handle 5A.)

It's been almost a year, but My M4 Pro MacBook Pro can finally do what my M1 MacBook air from years ago could - drive an external LCD monitor with a single USB cable. I can't believe it took nearly a year to release an update for this, but can also confirm it finally works.

WORKING PORTABLE MONITOR! Viewsonic VA1655, with SINGLE USB-C Cable on 16inch m4 pro MacBook Pro

just updating whoever its relevant to, intehill U16ZT works fine with a single-cable for display, power and touch. good resolution too, HIDPI at 1530X960, using with macbook pro m4 pro chip

I just wanted to add a few additional data points to this bug. I work in cybersecurity and am a long-time Mac user and power user. My travel laptop is an M3 Macbook Air. My daily driver between work and home is a M4 Macbook Pro. I recently purchased a UPERFECT 4K portable monitor, and my M4MBP would not recognize it without the monitor's auxiliary USB-C power adapter and cable plugged into an outlet. My M3 Macbook Air recognizes the monitor without the monitor's auxiliary power plugged in and works perfectly. I suspected the cheap USB-C cables that were shipped with the monitor, even though they worked perfectly on the M3 Macbook Air. I ran out to Target and purchased an Apple Thunderbolt 4 cable, and I still had the same issue with the M4 Macbook Pro. So, what can we infer from these data points?

• The Macbook Air has 2 USB4 ports that support : (Charging, DisplayPort, and Thunderbolt3)

• The M4 Macbook Pro has 3 Thunderbolt 5 (USB-c) ports that support (Charging, DisplayPort and Thunderbolt5)

The issue, in my mind, lies with Apple with their implementation of TB5. Disappointing, to say the least. I am now returning the monitor to Amazon and the TB4 cable to Target... Uggh!

SOLUTION, more or less, I have the same Problem with my Verbatim 4k Portable Monitor but if you connect the USB C and the HDMI than the Monitor worked. still not the perfect solution but like this its portable and you don't need a Powercable or Fuse or so when you are on the Road or so.

Hope a Solution comes because I bought my Monitor new and I don't wanna have to buy another one because of this.

btbwoo87 wrote:

bump

one reader posted here that all that was required for their display to work was the vendor to "Get with the Program" and make a small firmware change.

Solutions already posted include:

• Buy the model that works from the vendor cited

• pressuring the Vendor to make similar firmware changes

• Provide additional power with an external power adapter or an additional cable for power.

I did actually test with various cables and monitors and even compared to their MacBook Pro M4 with the regular, pro, and max chips. They and Apple, who was on the phone with me, advised it’s only the M4 Pro/Max MacBook Pros that have the TB5 ports and that the port PD protocol isn’t allowing power and av to be transmitted. So, I can actually get one monitor to work with external power, but that’s it. I was also unable to get any of the six unpowered hubs to work. This is just silly.

And I too believe it can be fixed with an older OS (not doing that though) or a software update, but they literally said it was the TB5 port configuration and set up to deliver less power to preserve the MacBook power.

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.

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

AndrewBergman wrote:

As indicated and cited above, both list support for DP over USB-C

USB-C (DIsplayPort Alt Mode) support refers to video signal – not to the provision of operating power.

So far, it sounds like the main issue is with these monitors wanting more power than a USB-C / USB4 / TB host port is required to provide. For whatever reason (intentional or not), the older MBPs provided "enough" extra power, and the newer ones are not doing so.

If there is a problem with the monitors not working with the DisplayPort Alt Mode signal from a Mac's TB5 port, when they have enough operating power (from other sources), that could be an issue, too, but it would be one which logically would involve a different part of the system than Power Delivery negotiation/provision.

Positive. The Apple Store staff was baffled. They had no answer. We looked at all of their M4 Pro and Max machines. All hardware profiles said Thunderbolt 4.