USB-C can reach 120Gbps with the recently released USB4 version 2.0 specification
We’ve said it before, and we’ll say it again: USB-C is confusing. A USB-C port or cable can support a range of speeds, power capabilities and other features, depending on the specification used. Today, USB-C can support different data transfer rates, from 0.48Gbps (USB 2.0) up to 40Gbps (USB4, Thunderbolt 3 and Thunderbolt 4). Things will only intensify because today the USB Implementers Forum (USB-IF) published USB4 version 2.0 specification. It adds optional support for 80Gbps bi-directional bandwidth, as well as the optional ability to send or receive data at speeds up to 120Gbps.
USB-IF was the first to give us the floor USB4 version 2.0 September, saying it will support data transfer rates of up to 80Gbps in both directions (40Gbps per lane, four lanes in total), thanks to a new physical layer (PHY) architecture based on PAM-3 signal coding. For what it’s worth, Intel also demonstrated Thunderbolt at 80Gbps but it has not released the official specification yet.
USB4 version 2.0 offers a nice, potential advantage over the original USB4 specification, which introduced optional support for 40Gbps operation. You just have to be sure to check the specs to know what kind of performance you’re getting.
When USB4 version 2.0 products come out, you will be able to achieve 80Gbps with USB-C passive cables that currently run at 40Gbps, but you’ll need to buy a new cable if you want the longer, active 80Gbps.
120Gbps is optional
Today, USB-IF confirmed that USB4 version 2.0 will take things even further by optionally supporting data transfer speeds of up to 120 Gbps on three lanes.
“Optionally for certain applications, such as driving very high-performance USB4-based displays, the USB Type-C signaling interface can be asymmetrically configured to deliver up to 120Gbps in one direction while retaining 40Gbps in the other direction,” USB-IF- this announcement stands.
Typically, a USB4 version 2.0 port that supports 120Gbps operation will both transmit and receive data at 80Gbps. When the product is connected to the port, “a USB4 discovery process managed by the system software will determine whether the preferred mode of operation is the 120Gbps configuration. After initially connecting to 80Gbps, the port will then transition to 120Gbps operation,” said Brad Saunders, USB – said for Ars Technica, President and CEO of IF.
The new specification supports both data transmission and reception at 120Gbps; however, Saunders said the “most likely” application would see data sent from a PC to a high-performance monitor at 120Gbps, with 40Gbps of bandwidth available to send data to the system.
The new USB-C specification will appeal to setups with extreme display needs, including resolutions above 4K, player level refresh rates, HDR color and multiple monitors. Bandwidth demands from creators and gamers continue to push the 40Gbps limit of the original specification.
We could also see external SSDs and external GPUs that also use the USB4 Version 2.0 protocol. But both remain more niche products, even among today’s USB4 and Thunderbolt options.
The new USB4 Version 2.0 specification also includes support for USB 3.2 tunneling at 20Gbps, compared to 10Gbps before. And the new protocol supports it DisplayPort 2.1 specifications released by VESA today, plus PCIe 4.0.
With the USB4 version 2.0 specification released today, we don’t expect to see follow-up products for “at least 12 to 18 months,” USB-IF said in a statement to CNET.
However, when those products do come out, USB-IF hopes they won’t be presented to consumers as “USB4 version 2.0” or even some sort of “SuperSpeed USB.” After 12 years, USB-IF no longer recommends that vendors use terms like “SuperSpeed USB 20Gbps” (for a specification called USB 3.2 Gen 2×2, for example) and instead opt for names like “USB 20Gbps.”
If USB-IF had its way, products using its new open standard would be described as “USB 80Gbps”. Ultimately though, USB-IF has no control over this, and you’ll find that many manufacturers don’t list USB speeds, and some use spec names, like USB4 version 2.0. The Recommended USB-IF logos focus on speed and power delivery.
Name complaints and potential confusion aside, the new USB4 Version 2.0 standard offers technology that adapts to our evolving needs as products become more bandwidth-hungry and USB-C becomes ubiquitous, and in some places mandatory connector.
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