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 capacities, and other features, depending on the specifications used. Today, USB-C can support a variety of data transfer rates, from 0.48 Gbps (USB 2.0) to 40 Gbps (USB4, Thunderbolt 3, and Thunderbolt 4). Things are only about to heat up because today the USB Implementers Forum (USB-IF) released the USB4 Version 2.0 specification. It adds optional support for 80 Gbps bi-directional bandwidth as well as the optional ability to send or receive data at up to 120 Gbps.
USB-IF first announced USB4 version 2.0 to us in September, claiming that it would support a data transfer rate of up to 80Gbps in both directions (40Gbps /s 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 has also demoed 80 Gbps Thunderbolt but hasn’t released any official specs yet.
USB4 version 2.0 offers a potentially nice improvement over the original USB4 specification, which introduced optional support for 40Gbps operation. You just have to make sure to check the spec sheets to find out what kind of performance you’re getting.
Once USB4 version 2.0 products are released, you’ll be able to hit 80 Gbps with passive USB-C cables that currently run at 40 Gbps, but you’ll need to purchase a new cable if you want longer active 80 Gbps.
120Gbps is optional
Today, USB-IF confirmed that USB4 version 2.0 will go one step further by possibly supporting a data transfer rate of up to 120 Gbps over three lanes.
“Optional for certain applications, such as driving ultra-high performance USB4 displays, the USB Type-C signal interface can be configured asymmetrically to deliver up to 120 Gbps in one direction, while retaining 40 Gbps in the other direction,” the USB-IF announcement said.
Typically, a USB4 version 2.0 port that supports 120 Gbps operation will both transmit and receive 80 Gbps data. When a product connects to the port, “the USB4 discovery process handled by the system software will determine if the preferred mode of operation is the 120 Gbps configuration. After an initial connection at 80 Gbps, the port will then go to 120 Gbps operation,” Brad Saunders, USB – IF Chairman and CEO, told Ars Technica.
The new specification supports both 120 Gbps data transmission and reception; however, Saunders said the “most likely” application will see data sent from a computer to a high-performance monitor at 120 Gbps, with a 40 Gbps lane available to send data to the system.
The new USB-C spec will appeal to setups with extreme display needs, including resolutions beyond 4K, gamer-level refresh rates, HDR color, and multiple monitors. Bandwidth demands from creators and gamers continue to push the original specification’s 40 Gbps limit.
We might also see external SSDs and external GPUs also using the USB4 Version 2.0 protocol. But both remain 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 20 Gbps, up from 10 Gbps previously. And the new protocol supports the DisplayPort 2.1 specification announced today by VESA, as well as PCIe 4.0.
With the USB4 version 2.0 specification released today, we don’t expect to see supported products for “at least 12 to 18 months,” USB-IF said in a statement to CNET.
When these products come out, however, USB-IF hopes they won’t be presented to consumers as “USB4 Version 2.0” or even some type of “SuperSpeed USB”. After 12 years, USB-IF no longer recommends vendors use terms like “SuperSpeed USB 20Gbps” (for the specification called USB 3.2 Gen 2×2, for example) and instead opts for names like ” USB 20Gbps”.
If USB-IF were successful, products using its new open standard would be described as “USB 80 Gbps”. Ultimately, however, the USB-IF has no control over this, and you’ll see many vendors not listing USB speeds, and some using spec names, like USB4 Version 2.0. USB-IF recommended logos focus on speed and power delivery.
USB-IF also updated the specifications of the USB Type-C cable and connector and USB power supply today to support version 2.0 of USB4.
Name complaints and potential confusion aside, the new USB4 version 2.0 standard offers the technology to adapt to our ever-changing needs as products become more bandwidth-intensive and USB-C becomes more ubiquitous and, in some places, the mandatory connector.
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