Apple added a Thunderbolt (USB-C) port to the M1 series of Mac computers, which can support USB 3.1 Gen 2, up to 10Gp/s speed, but it was found by foreign users that the external transmission speed might not reach 10Gb/s. Both Thunderbolt 3 and Thunderbolt 4 have the same problem.
Many users have found that the Mac Thunderbolt (USB-C) port transfer speed cannot reach the official USB 3.1 Gen 2 speed, but Apple’s official website clearly states that Thunderbolt 4 can support USB 3.1 Gen 2 (up to 10Gb/s), USB 4 (up to 40GB/s) high-speed transmission, in order to verify whether there is really a problem with Thunderbolt, the foreign Eclectic Light website measured the Thunderbolt speed through two new-generation M1 Mac computers. The specifications are as follows:
- Apple Mac Studio with M1 Max, 32GB RAM, 2TB SSD
- 2021 MacBook Pro 16-inch with M1 Pro, 32GB RAM, 2TB SSD
Both devices were run in macOS 12.3.1 Safe Mode, in APFS format, and tested with Crucial Micron and Samsung SSDs, both external devices were tested by iMac Pro for USB 3.1 Gen 2 speed, and finally Verified with two M1 series Macs.
M1 Mac Thunderbolt Test Summary
Eclectic Light The results of the two Thunderbolt 4 tests found that since November 2020, Apple’s Thunderbolt ports on any M1 models are almost unable to support USB 3.1 Gen 2, resulting in a speed that cannot reach 10Gb/s.
- Inateck SATA RAID SSD and SanDisk Extreme Portable measured speed: read 390MB/s, write 418MB/s (will limit USB 3.1 Gen 2 read and write speed to 5 Gb/s)
- Sabrent+Samsung NVMe measured speed: read 911MB/s, write 973MB/s (complies with USB 3.2 speed)
Some people may think it’s an external SSD problem, but in fact, both devices have passed the iMac Pro test and verified that the speed can reach USB 3.1 Gen 2 is quite normal. Testers also believe that SATA/USB-C storage has a limited impact on performance, but the Thunderbolt 4 transfer speed will limit USB 3.1 Gen 2 to a maximum of 5Gb/s, resulting in read and write speeds down to regarding 418 MB/s. very problematic.
Currently, only the two USB-C ports on the front of the Mac Studio can really achieve 10Gb/s speed, or support USB 3.1 Gen 2 for external devices. It should be connected to the Thunderbolt 3 Dock or the USB-C port on the Studio Display for transmission performance. will be better.
In this regard, Apple should also start investigating the problem of Thunderbolt 4 port compatibility, which, together with the Mac Studio front panel, sometimes degrades USB-C transmission performance by regarding 10%.
Eclectic Light thinks Apple should start looking into the Thunderbolt 4 port compatibility issue, which has been around for more than a year and is present on almost all M1 Macs, including the new Mac Studio just launched this year.
If the problem is a firmware bug in the Fabric core, it should have been fixed a year ago, and if the M1 series chip compatibility fails, then Apple should send a notification to warn users of Thunderbolt compatibility issues as soon as possible.
At present, Mr. Crazy has reported this issue to relevant Apple personnel, and is waiting for follow-up investigation and response. This article will also update Apple’s official follow-up response.
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