Yesterday, the USB Promoter Group revealed the next evolution of its ubiquitous peripheral spec: USB4. The new specification, which is still a draft in the final stages of review, is based on Intel's Thunderbolt 3 protocol, delivering up to 40Gbps throughput over existing, Thunderbolt spec-certified Type-C cables. That's twice as fast as current USB 3.2 maximums. It's also backward compatible with existing USB 3.2, 2.0, and Thunderbolt 3 specs and devices.

This news comes hot on the heels of a bulk renaming of existing USB 3-based specs, so that USB 3.2 backward compatibility inherent in USB4 presumably covers the spec formerly known as USB 3.1 Gen 1 (which was once USB 3.0) and the spec once called USB 3.1 Gen 2 (which was once USB 3.1), as they're all just different USB 3.2 versions now.

It's a confusing mess, I know.

The still nascent USB4 spec may provide double the bandwidth of USB 3.2, but it actually just matches the speed of Intel's existing Thunderbolt 3 spec. Presumably, it will also deliver Thunderbolt's PCI Express protocol support, which can power such magic as external GPUs, in the right configuration. Basically, all the things that Thunderbolt 3 can do — like dual 4K 60fps monitor support, 100W charging, etc. — USB 4 should be able to.

Thunderbolt 3, 2, and 1 (down the middle, center) on Apple's Macbook Pro over the years. Previous implementations used the DisplayPort connector.

Considering how many phone OEMs are still just using what is effectively USB 2 over a Type-C connector, it could be quite a long wait until we see USB4 arrive in any handsets, but Chromebooks and other laptops should see the benefits sooner. The spec is expected to be finalized and published around the middle of this year, together with a compatibility update to the Type-C spec to accommodate it. Assuming OEMs don't start work on devices which include it until after that point, we're looking at a year or two wait.

It's a bit surprising that Intel would just up and license out its Thunderbolt tech to the USB Implementer's Forum/Promoter Group; presumably, it was making a good chunk of change licensing the tech to Apple and other OEMs. Still, Jason Ziller, General Manager of the Client Connectivity division at Intel, is unfazed. "By collaborating with the USB Promoter Group, we’re opening the doors for innovation across a wide range of devices and increasing compatibility to deliver better experiences to consumers."

The Verge was also told that the new USB4 spec will attempt to impose more strict requirements on the features different types of devices must support — though there's still no actual enforcement mechanism. It's an open standard, after all.

USB peripherals and accessories will always be something of a wild west scene, given the risk inherent with incomplete or out of spec implementations in an open standard, but at least the still-risky future is looking a bit faster.

PRESS RELEASE