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I have a Macbook Air M1 running MacOS 13.3.1 and I tried a DELL monitor on the other day.

This is the DELL monitor spec:

Screen Size: 31.5 in (80.01cm)

Resolution: 1440p WQHD

Native Resolution: QHD (2 560 x 1 440)

Aspect Ratio: 16:9

Static Contrast Ratio: 1,000:1

USB-C port

I tried to plug my M1 into the monitor via the USB-C cable provided by DELL and it worked out well. I must highlight that the monitor was connected to the electricity.

Thus, I decided to try the same, but this time using my USB-C cable from Apple. Usually, I use this cable to charge my MacBook air.

It was possible to see that the MacBook started charging the battery though the monitor. However, the image display did not work out. My MacBook was not recognizing the existence of the DELL Monitor as it did before. I could not see it on "System Preferences > Displays".

In order to reduce bias, I also tried the same experiment with my wife's MacBook Air (not a M1) USB-c power cable. And I experienced the same results. It worked as a way to charge the MacBook, but it did not work out for the image display.

Why is that so? Isn't the USB-C cable provided by Apple supposed to support image display?

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    If you read the Charge Your MacBook…. support document, you’ll notice they always refer to a “USB-C charge cable.” This (IMO) is a sneaky way of saying “this is not a full USB-C cable, but a charge and sync cable.” At the price point of an MBA and the super low cost of a decent USB-C, I don’t see what costs they are saving by doing this.
    – Allan
    Jun 6, 2023 at 20:59
  • 1
    Related: discussions.apple.com/thread/…
    – Thinkr
    Jun 7, 2023 at 5:52

1 Answer 1

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Apple USB-C charging cables support only USB 2.0. Calling them "charging cables" is a bit of a misnomer since they do more than charge but I suspect they label them for charging only to discourage use for anything else.

As an example someone could use such a cable to connect a USB-C hard drive and have it work at USB 2.0 speeds, then complain to Apple about the low data rate. Apple can reply that they only guarantee that the cable will supply power, that is why it is called a "charging cable".

Why limit the cable to USB 2.0? It makes them cheaper to produce. Also, the way USB-C and USB power negotiation work means that by limiting the data to USB 2.0 they can supply 2 meter long cables without complicating things and still meet USB specifications on data and power.

There are certainly USB-C cables that are 2 meters long and will still support USB 3.1 data, DisplayPort, Thunderbolt, and other data beyond just USB 2.0 but these cost more to make. Apple is providing a cable to connect the computer to the power brick, and by keeping the cable cheaper they pass the savings on to you. (Yes, I know there's all kinds of jokes that could be made about profit margins but just roll with me here.)

If anyone were to look closely in the Apple support documents there is a mention of supporting USB 2.0 with the charging cable. This can come in handy for moving data in a pinch if there's nothing else available.

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