USB has undergone a couple of big changes recently, what with the introduction of USB 3.2, the renaming of previous USB specifications, and the announcement of the USB4 standard. Let’s try to simplify them here and what it means for users.
USB 3.2 GEN 2X2
USB 3.2 has been talked about since 2017 and it is finally here. This is the latest specification of the USB 3 group of standards and it promises transfer speeds of up to 20Gbps - the maximum attainable on a USB-C cable. It achieves this using two highspeed USB-C channels. You will see it being marketed on devices under the name SuperSpeed USB 20Gbps. USB 3.2 Gen 2x2 will only be available using a USB-C connector.
USB 3.2 GEN 2
This is what used to be known as USB 3.1 Gen 2. The maximum transfer speed is 10Gbps and it can use either a USB-C or USB-A connector. You will see it being marketed on devices under the name SuperSpeed USB 10Gbps or SuperSpeed+ USB 10Gbps.
USB 3.2 GEN 1
This is what used to be known as USB 3.1 Gen 1 which was previously known simply as USB 3.0 The maximum transfer speed is 5Gbps and it can use either a USB-C or USB-A connector. You will see it being marketed on devices under the name SuperSpeed USB.
Intel promised that it would make Thunderbolt 3 open and royalty free and it has finally happened. USB4 (yes, without a space) is based on the Thunderbolt 3 protocol and it supports just about everything Thunderbolt 3 can. This means a maximum data transfer rate of 40Gbps, power delivery of up to 100W, and the ability to drive two 4K displays or a single 5K display. On top of that, it will also be backward compatible with older USB standards such as USB 3 and 2. USB4 will only use USB-C connectors.
There are, however, some caveats. First of all, you need a good quality cable to achieve the maximum data transfer rate of 40Gbps. That said, older cables will work, but they will only operate at their (the cable’s) maximum rated speeds. So an old USB 3.0 cable will only get 5Gbps even if it is plugged into a USB4-capable port.
While USB4 is based on the Thunderbolt 3 protocol, not all USB4 implementations will work properly with Thunderbolt 3 devices. This is because Thunderbolt compatibility is not a requirement of the USB4 specification. Furthermore, any product that wants to market itself as Thunderbolt compatible needs to be certified by Intel. Manufacturers might choose not to do that as products need to undergo a rigorous validation process that adds cost to the product. That said, the USB Promoter Group expects most USB4 enabled devices to be compatible with Thunderbolt 3 accessories and device, but no guarantees.
PICTURE 123RF, THUNDERBOLT
In a nuteshell, Thunderbolt 3 cables and devices will get the most out of USB4, but not all USB4 implementations will work with Thunderbolt 3.