Skip to main content

M1 Macs could have a problem with their Thunderbolt ports

Imagine paying for an expensive Mac only to discover you’re not getting full Thunderbolt 4 speeds. That’s what some M1 Mac pro users are reporting after several transfer speed tests.

Howard Oakley from Eclectic Light performed different tests with the 2021 16-inch M1 Max MacBook Pro and a 2022 Mac Studio, also with the M1 Max. He also used a range of external SSDs from both Crucial and Samsung. The tests suggests that although both Macs support Thunderbolt 4, they don’t support the USB 3.1 Gen 2 standard, hindering transfer speeds.

A side profile of the 2021 MacBook Pro.
Digital Trends

Oakley first determined what the theoretical speeds were by connecting the external SSDs to an Intel iMac Pro and verified that USB 3.1 Gen 2 was supported. For context, USB 3.1 Gen can transfer up to 10 Gb/s. He also ensured that only certified Thunderbolt 4 cables were used.

The actual tests included transferring 160 files ranging in size from 2 MB to 2 GB. As a control, the Intel iMac Pro recorded 470 MB/s read speeds and 480 MB/s write speeds. By contrast, Oakley confirmed that read speeds on M1 Macs ranged between 386 Mb/s and 406 Mb/s while write speeds were between 430-435 MB/s.

Connecting to one of the two ports on the front of the Mac Studio using a Thunderbolt 4 cable produced terrible performance at 20 MB/s reads and 37 MB/s writes.

Here is a summary of the results:

  • USB 3.1 Gen 2 storage connected direct to a Thunderbolt port on an M1 Mac was limited to 5 Gb/s, giving read rates of about 400 MB/s and write rates of about 430 MB/s.
  • USB 3.1 Gen 2 storage connected to a USB-C port on the front of a Mac Studio Max using a USB-C cable, or via a USB-C port on a Studio Display, operated at 10 Gb/s, with read and write rates of about 500 Mb/s and 490 MB/s.
  • USB 3.2 storage connected directly to a Thunderbolt port on an M1 Mac operated at 10 Gb/s, with read and write rates of about 910 Mb/s and 970 MB/s.
  • USB 3.1 Gen 2 storage connected to a USB-C port on the front of a Mac Studio Max using a Thunderbolt 4 cable operated at 10 Gb/s, but read and write speeds were lowest of all, at about 20 and 40 MB/s.

At the end, Oakley offers several conclusion and recommendations, one of which is for those with USB 3.1 Gen 2 devices to use Thunderbolt 3 docks or the USB ports on the Studio Display. He also mentions that Apple should have informed people about slower transfer speeds or issued a firmware patch if the slow speeds are due to bugs.

Admittedly, with the exception of the front USB ports on the Mac Studio, the transfer speeds aren’t terrible compared to the actual USB 3.1 Gen 2 spec. However, with customers paying at least $2,000 for a base M1 Pro MacBook Pro and M1 Max Mac Studio, one would hope to get the full Thunderbolt 4 speeds.

Editors' Recommendations

David Matthews
Former Digital Trends Contributor
David is a freelance journalist based just outside of Washington D.C. specializing in consumer technology and gaming. He has…
Apple did the unthinkable with the new M4 chip
Apple introducing the new M4 chip.

Apple is doing something crazy with its new M4 chip. Although we're used to seeing new Apple silicon debut in Macs, Apple is bringing the M4 chip to the new iPad Pro first. The updated chip, which comes with an entirely new CPU architecture, builds on the GPU found in the M3 chip with ray tracing, mesh shading, and Apple's special Dynamic Cache.

With the M4, Apple says the new iPad Pro can deliver the same performance as a thin-and-light PC while using only a quarter of the power. That's due in no small part to the 3nm architecture the chip uses. The power envelope, according to Apple's claims, is all the more impressive considering the iPad Pro doesn't have any active cooling.

Read more
Apple has backed itself into a corner
Apple iPad Pro 11 with Apple Magic Keyboard.

Apple is rumored to finally be updating its new iPads at its forthcoming May 7 event. While this may come as a relief to anyone who’s been patiently waiting to upgrade their iPad Pro or iPad Air, a new report has thrown the whole situation into confusion.

That’s because the latest Power On newsletter from Bloomberg reporter Mark Gurman claims that the upcoming iPad Pro will contain an Apple M4 chip. On first blush, that doesn’t seem all that unusual -- the iPad Pro has come with an Apple silicon chip for years, after all. But here’s the wrinkle: this launch plan would mean the iPad will get an M4 chip before the Mac, and that has all kinds of weird implications. By delaying the iPad for so long, it looks like Apple has left itself with a very odd update cycle for its chips this time around.
The end of the M3 Ultra?

Read more
The XPS 16 is fighting an uphill battle against the MacBook Pro
Dell XPS 16 sitting on desktop with flowers.

It took a few years, but Dell finally updated the design of its two largest XPS laptops. The XPS 15 gave way to the XPS 14, while the XPS 17 was replaced by the XPS 16. The latter gained the ultramodern look of the XPS 13 Plus, complete with a glass palm rest, a hidden haptic touchpad, and a row of LED function keys.

It's a significant update but places the XPS 16 in direct competition with the Apple MacBook Pro 16. That's an excellent matchup with proven performance and battery life and an elegant design that's solid, if a lot more conservative.
Specs and configurations

Read more