Mac M1, no USB 3.1 Gen 2 (10Gb/s) support in Thunderbolt 4 ports?

In recent years this has been done some confusion around USB standards, with the specification of USB version 3.1 which has been modified several times. The latest specs list a maximum transfer rate of 10Gb/s for the technology, but not all computers with USB 3.1 ports will necessarily reach this speed. This happens, in fact, even with the most recent Macs equipped with Apple Silicon, as shown by some tests carried out by Howard Oakley of Eclectic Light.

Mac M1 and unit


A bit of history: the USB 3.1 standard dates from 2013 and comes in two variants: January 1st And January 2. The former retains USB 3.0’s SuperSpeed ​​transfer mode, which theoretically enables data transfer speeds of up to 5 Gb/s. With USB 3.1 Gen 2, the transfer speed doubles to 10 Gbps. Then there is an even more efficient standard, USB 3.2, released in 2017 and capable of supporting SuperSpeed+ data transfer mode up to 20 Gbps. Back to Apple: new Macs powered by Apple Silicon processors implement USB Type-C connectors with support for Thunderbolt 4, a protocol announced by Intel in early 2020 capable of reaching data bandwidth of up to 40 Gb/ s.

Mac M1, no support for 10Gbps SuperSpeed+ on USB 3.1 Gen 2 keys: hardware problem or software bug?


Thunderbolt 4 ports are featured on Apple MacBook Pro 16″ and on the recent mac studio, high-end systems that needed to support the USB 3.1 Gen 2 standard with a maximum transfer rate of up to 10 Gbps. But, in reality, it seems that the built-in ports achieve much lower data transfer rates in practice with devices compatible with the standard: after receiving several reports from users eclectic light tested the port speeds of the two systems mentioned above.

Specifically, Oakley tested an Apple Mac Studio with an M1 Max processor, 32GB of RAM and 2TB of internal SSD and a 2021 16-inch MacBook Pro with M1 Pro SoC, 32GB of storage and a 2TB internal SSD. Several external SSDs (including NVMe) were used for testing using certified Thunderbolt 4 cables and USB-C data cables.

On an Intel Mac, the source points out, all drives and cables reported SuperSpeed ​​​​+ 10 Gbps connections in the macOS System Information, with transfer rates (measured via the app Stibium 1.0 which transfers 160 files of sizes between 2MB and 2GB on an SSD folder) conforming to the limits of the standards. On Macs with M1 processors, performance was rather 10% lower when using SATA drives, and it seems that even newer Studio Macs don’t support the USB 3.1 Gen 2 standard. Here are the results of the tests carried out declared by the source:

  • Mac with Intel processor (USB Type-C cable, connection detected at 10 Gbps)
    • Read Speed: 470MB/s
    • Write Speed: 480MB/s

  • Mac M1 (USB Type-C or Thunderbolt 4 cable, 5Gb/s connection detected)
    • Read speed: 386 MB/s to 406 MB/s
    • Write Speed: 430MB/s to 435MB/s

The source was able to unlock the transfer speed of 10Gb/s on Mac Studio only by using USB 3.2 compatible storage drives, and achieve read and write speeds of 910MB/s and 970MB/s respectively only using the front doors of the office. Connecting SSDs via a Thunderbolt 4 cable to the same ports, however, performance drops dramatically (resulting in 20MB/s and 40MB/s in read and write speeds). In short, if on paper the ports of the new Mac M1 could reach very high speeds, in practice they seem clearly limited if we consider the tests carried out by Oakley.

Several conclusions can be read in the Eclectic Light article and we report the most interesting:

  • No Mac M1 model could support the SuperSpeed+ (10Gbps) standard of the USB 3.1 Gen 2 protocol (at least for SSDs). On the other hand, the SuperSpeed ​​+ (10 Gbps) standard of USB 3.2 is supported
  • If you’re using SATA SSDs, the performance hit is limited (about 500-400MB/s read and write), while it becomes more obvious if you’re using NVMe SSDs. In this case, it is also reasonable to expect a halving of the read and write transfer speed.
  • To unlock the full potential of these devices, you must use Thunderbolt 3 docking stations or the Studio Display USB ports if you are using the Apple monitor.

The source believes that it is possible that the problem is present on all M1 Macs released, and does not exclude that it is a software bug that can be contained relatively easily by Apple itself.


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