After giving hints about it earlier this year, the USB Implementers Forum (USB-IF) has now made the USB4 version 2.0 specification official. The new version of the USB specification says that four lanes can move up to 80Gbps of data in both directions. This will work with both the 40Gbps USB4 passive cables that are already in use and the new 80Gbps cables.
In addition to the 80Gbps of bandwidth in both directions, the new specification also has a new special mode where three of the four lanes can pass data in the same direction. This means you get 120Gbps of data in one direction and 40Gbps in the other direction. This specification is for certain uses, like very high-resolution displays, where it makes sense to have a lot of bandwidth going in one direction. Support for this capability, on the other hand, is not required.
Version 2.0 of USB4 specification.
Notably, the data and display protocols have also been improved in this new Version 2.0 of USB4 specification. The USB4 link now supports the new Enhanced SuperSpeed USB tunnelling for data, which means you can get up to 20Gbps of bandwidth just for data. That may sound strange, but most of the maximum bandwidth of a USB4 link is used for display signals or PCIe, so connecting an external drive to a 40Gbps port wouldn’t necessarily give you faster speeds.
DisplayPort 2.1, the latest version of this standard, is also built into USB4 version 2.0. It was released earlier this week. These changes are meant to work well together and make it easier to send a DisplayPort signal over a USB4 link. The new USB standard also works with PCIe 4.0, which should make external graphics cards work better on devices that can use them.
Along with the new USB specification, there are also new versions of the USB Type-C and USB Power Delivery certifications to match these new features. As a reminder, USB Power Delivery was just updated to support 240W, so USB-C ports are getting more and more useful quickly.
As usual with USB, a lot of these features are optional, so you’ll have to look at the logos on certified products to find out which features they support. The branding should show the maximum bandwidth and speed at which power can be sent (if power delivery is supported).
