USB4 2.0: What to expect

Just when you thought you had USB4 figured out, the USB overlords are here you teach you a lesson. On Thursday, the group managing USB dropped plans to soon introduce USB4 2.0 that will hit 80 Gbps data rates—double that of USB4.

The USB Promotors Group said USB4 version 2.0 aims to enable higher performance USB 3.2, DisplayPort and PCIe tunneling.

“Once again following USB tradition, this updated USB4 specification doubles data performance to deliver higher levels of functionality to the USB Type-C ecosystem,” said Brad Saunders, USB Promoter Group Chairman.”

Saunders didn’t mention the other tradition is cause everyone who had comfortably figured out USB head for the PDF spec sheets all over again.

USB4 2.0 will move to 80Gbps on a physical layer architecture which means it’s not just a tweak to the electrical signal such as just upping the clock speed. Don’t worry though—that collection of pricier USB4 Type C cables you have bought will still with the new spec. In fact, the USB PG said USB4 2.0 is based on the existing passive 40Gbps cables. Those long active cables will get a new spec to hit 80Gbps though we’d guess you’ll have to rebuy any long cable.

The USB-PG said the updates to the data and display protocols or the way the USB ports talk to USB devices will see USB 3.2 data tunneling that can exceed 20 Gbps and also allow for the latest versions of DisplayPort and PCIe.
USB 3.2 actually tops out at 10 Gbps using a single set of wires or “lane” and can reach 20 Gbps per lane when two are used. Even though USB 3.2 20 Gbps was rare on a PC, one does wonder why the new USB4 spec needs to exceed 20 Gbps. The USB PG didn’t say, but it’s possible the excess USB 3.2 throughput could be used to feed multiple USB 3.2 devices plugged into an external dock or monitor.

Also left unsaid by the USB-PG is just what it means by the latest specs of PCIe. Currently USB4 supports tunneling of PCIe using PCIe 3.0 and up to four lanes. The newest PC’s support PCIe 5.0 but since PCIe 5.0 is still uncommon, and not easy to implement, we’d assume USB4 version 2.0 will support PCIe 4.0. That’s still a welcome update over today’s USB4 for those who use external graphics enclosures and PCIe-based storage devices.

And of course, USB4 version 2.0 is backward compatible with USB4 1.0, USB 3.2, USB 2.0 and Thunderbolt 3.

Where’s Thunderbolt 5?

Obviously the big question is what’s up with Thunderbolt 5? USB4 1.0 is essentially based on the same tunneling design as Thunderbolt 3 which Intel released as a royalty free standard in 2017. In fact, Thunderbolt 4 is essentially feature-for-feature the same as the full implementation of USB4 1.0.

With USB4 now available from Intel, Apple and AMD, many have wondered if Intel needed to even carry on with Thunderbolt 5 having essentially achieved its long-term goal of “one cable, and one connector to rule them all.”

The thing is, as early as August of 2021, Intel executive Gregory Bryant posted a whoopsie Tweet that featured a photo showing Thunderbolt 5 at 80Gbps data rates using PAM-3 modulation technology which let’s a signal carry a -1, 0 or +1 rather than the more conventional 0 or 1 today. Bryant deleted the photo soon after, but as we know the all seeing eye of the Internet caught it. In fact, Anandtech’s Dr. Ian Cutress covered it here soon after and discusses the protocol as well as its relation to USB.

In the end, this all means more speed—but likely only with newer USB4 2.0 laptops or Thunderbolt 5 laptops.

You’ll have to wait

If you’re spying a new laptop or desktop that support USB4 2.0, you’re likely going to have to wait. Today’s news is just a news announcement. The actual spec gets unveiled in November to developers. It has typically taken a year or two to see it implemented in hardware and available for purchase. So no, don’t worry about USB4 version 2 in any laptop you want this year and probably even next year.

And if you’re screaming over the idea of USB4 version 2.0 you may want to take a chill pill. While the spec is called USB4 version 2.0, the final name that consumers will see hasn’t been announced yet. So yes, maybe we’ll see USB4 Super Duper Speed in laptops by 2024.