The Eclectic Light Company recently carried out some interesting tests on the Thunderbolt 4 port of Apple silicon Macs. You should know that on paper, the Thunderbolt 4 ports of Apple computers equipped with an M1 chip are USB 3.1 Gen2 compatible.
However, this USB connection is theoretically capable of reaching a maximum transfer speed of 10 GB/s. In practice, as the source indicates, it is rather a question of considering a maximum speed of 1200 MB/s.
The Eclectic Light Company has therefore compared an external SSD connected to USB-C on Mac Intel and on Mac Apple silicon M1. On Intel Macs, with SSD connected directly via USB 3.1 Gen2, read speeds were around 470 MB/s in reading and 480 MB/s in writing.
On the M1 Macs tested, the SSD was plugged into a Thunderbolt 4 port via a USB-C cable or a Thunderbolt 4 cable. In all cases, read and write speeds were much lower: nearly 400 MB/s and 430 MB/s respectively.
Further testing of the machines’ various Thunderbolt and USB ports showed limited speeds for Thunderbolt 4 compared to what the USB 3.1 Gen2 standard normally allows.
Here are the conclusions of the in-depth analysis by The Eclectic Light Company: on Mac M1, even on Mac Studio, Thunderbolt 4 ports do not fully support USB 3.1 Gen2.
This is a rather alarming finding given that Apple affirms black on white that its Thunderbolt 4 ports on Mac Apple silicon do indeed support USB 3.1 Gen2 with a maximum speed of 10 Gb/s. Especially since the problem affects machines like the recent Mac Studio, which, as its name suggests, is intended mainly for creative studios. However, in the latter and for audio, photo and video specialists, transfer speeds with external storage are of great importance.
Worst of all: using a Thunderbolt 3 dock for example, or taking advantage of a Studio Display USB port, read and write speeds for external USB 3.1 Gen2 SSD storage are much better than plugging into a Thunderbolt 4 port built into the Mac…