Howard Oakley of The Eclectic Light Company has been doing some testing of the Thunderbolt ports on M1 Macs, and it seems that real-world performance doesn't match Apple's claims. When using USB 3.
1 Gen 2 devices with M1 Mac Thunderbolt ports, performance doesn't meet the expected connection speeds of up to 10Gb/s, meaning real-world read/write speeds will also fall short of expectations.
Before diving into Oakley's test results, it's important to understand the USB 3. x standards. As outlined by Oakley, USB 3. 0 supports SuperSpeed USB at 5Gb/s. USB 3. 1 Gen 2 includes SuperSpeed+, which doubles the possible speeds to 10Gb/s. USB 3. 2 allows for two-lane SuperSpeed+, doubling the maximum possible speed yet again to 20Gb/s.
Apple's M1 Macs are equipped with Thunderbolt 4, which supports speeds up to 40Gb/s using Thunderbolt 4-equipped storage and supports USB 4, which is also up to 40Gb/s. While Apple doesn't explicitly mention USB 3. 1 Gen 2 on its list of tech specs for M1 Macs, users reasonably expect that Thunderbolt 4 ports that support USB 4 would deliver the (lesser) speeds of USB 3. 1 Gen 2. However, users have found that their M1 Macs don't meet this expectation.
The M1-equipped MacBook Pro (14- and 16-inch models) have three Thunderbolt 4 ports. These ports support speeds up to 40Gb/s, so why are USB 3. 1 Gen 2 devices not delivering the expected speeds?
Oakley's results confirm the underwhelming performance. He performed testing with an Apple Mac Studio with an M1 Max chip and a 16-inch MacBook Pro with an M1 Pro chip. In both cases, the computers ran macOS 12. 3. 1 in Full Security Mode with no extensions enabled that might affect transfer speeds. To measure transfer rates, Oakley used his app, Stibium. When using Thunderbolt 4 ports on an M1 Mac with certified USB-C and Thunderbolt 4 cables, the connection speed was 5Gb/s. However, when using USB-C ports, like the pair of ports on the front of the M1 Max Mac Studio, the connection speed was 10 Gb/s. Further, when connected to an Intel Mac using a USB-C cable, the connection speed was 10Gb/s.
What does all this mean? USB 3. 1 Gen 2 storage connected to an M1 Mac via a Thunderbolt 4 port delivered 5Gb/s connection speeds. When connected to a USB-C port, like on the front of the new Mac Studio Max desktop computer, the connection speed was 10Gb/s. USB 3. 2 storage, which can operate at up to a 20Gb/s connection speed, was 10Gb/s when connected to a Thunderbolt port on an M1 Mac. Given the halved connection speed, if you are using USB 3. 1 Gen 2 storage, read/write speeds will correspondingly be about half of what users expect when using a Thunderbolt port on an M1 Mac.
Oakley concludes that if the shortcoming is a bug, 'it should have been fixed over a year ago. ' If it's not a bug, but is a defect of the M1 chip family itself, 'then Apple should have informed users and qualified its claim for the compatibility of these ports. ' 9to5Mac has reached out to Apple for comment. It will be interesting to see what Apple says if they respond. For the full breakdown of Oakley's results, click here.
. dpreview.com2022-4-20 16:10