USB 4 will support 8K and 16K displays. Here's how it'll work

With DisplayPort 2.0 support, next-generation USB technology should help PC makers banish another port starting in 2021.

Stephen Shankland principal writer
Stephen Shankland has been a reporter at CNET since 1998 and writes about processors, digital photography, AI, quantum computing, computer science, materials science, supercomputers, drones, browsers, 3D printing, USB, and new computing technology in general. He has a soft spot in his heart for standards groups and I/O interfaces. His first big scoop was about radioactive cat poop.
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Stephen Shankland
4 min read
USB-C ports in 2021 could handle 8K displays thanks to DisplayPort support arriving in 2021.

USB-C ports in 2021 could handle 8K displays, thanks to DisplayPort support arriving in 2021.

Stephen Shankland/CNET

USB 4, the next incarnation of the ubiquitous data-transfer technology, will be fast and versatile enough to let you plug a very high resolution 8K display in to your PC. That's because it'll accommodate DisplayPort 2.0, the newer version of a standard widely used to connect external monitors.

The move, which industry groups announced Thursday, means USB will be a more capable replacement for older-style ports on digital devices -- and that computers will likely rely more on the increasingly versatile port. However, the versatility brings new complications when you're trying to figure out if devices, ports and cables support particular abilities you'd like.

As PC and phone makers have sought to shrink and simplify their designs, USB ports have absorbed more and more duties once handled by specialized ports for things like printers, power cables, earphones, network cables and external displays. Check below for details on how DisplayPort will work over USB when it's time to plug in a display.

USB 4 could arrive as soon as this year, doubling data transfer speeds and increasing the flexibility compared with today's USB 3. But DisplayPort 2.0 support won't reach USB 4 until 2021, according to VESA, the industry group that develops DisplayPort. It developed the technology in cooperation with the USB Implementers Forum that oversees USB.

DisplayPort will work on USB 4 by using an "alt mode" that essentially changes the data-transfer language a USB port is speaking, but it'll still be able to send USB data and support the USB Power Delivery technology used to deliver electrical power.

Supporting 8K and 16K displays on USB 4

You may not run into today's speed limits for displays and video, but gamers and creative professionals often use enormous monitors, and supporting DisplayPort 2.0 could mean they can do what they want. VESA released the standard in 2019, tripling data-transfer speeds to support 8K displays -- 7,680x4,320 pixel resolution -- at a 60Hz refresh rate with full color. With some compression, DisplayPort 2.0 also can support 16K (15,360x8,460 pixels) displays, too. VR displays also benefit from high resolution.

USB 4 gets much of its power by absorbing technology Intel developed for its Thunderbolt port technology. Thunderbolt 3 a few years ago adopted the USB-C physical connector and today runs as a USB alt mode.

USB 3 can use either new and old USB ports -- the more recently developed oval-shaped and reversible USB-C connectors that you see on new phones and laptops or the rectangular USB-A ports that've been on computers for two decades. USB 4, though, will require USB-C connectors.

USB 2 reached a data transfer speed of 480Mbps. USB 3 in principle can reach 20Gbps, though it's most commonly implemented only at 5GBps or 10Gbps today. USB 4 will be able to reach 40Gbps, the speed of Thunderbolt 3.

How DisplayPort over USB 4 will work

USB and video have gotten along awkwardly in the past. But DisplayPort support is a required feature of USB 4, said Craig Wiley, senior marketing director at display company Parade Technologies and leader of VESA's work on integrating the two standards.

Any devices like phones, tablets and PCs that support display technology have to support DisplayPort, he said. That applies to USB docking stations as well, which in VESA's world means devices that plug into a USB port to offer a range of other ports, like video, SD card readers and Ethernet jacks.

Watch this: USB4: What you need to know

That means you'll be able to plug your DisplayPort monitor into a USB 4 docking station, not just directly into a USB 4 port, Wiley said. However, the video support isn't guaranteed for USB hubs, which VESA defines as dongles that just offer multiple USB ports without other connectors.

Another nice perk: With USB's newer power abilities, you'll be able to power your laptop from a plugged-in external monitor, too, Wiley said.

And because USB 4 uses Thunderbolt's "tunneling" technology, which can pack several types of data transfer into one data connection, you'll be able to do things like plug USB keyboards and external drives into your USB-connected DisplayPort display. 

USB versatility brings complications

USB's versatility -- increasing with USB 4 -- comes with some difficulties, though. In earlier days, computers had separate ports for video, audio, networking, power and other needs. USB can handle all those things and more -- but you don't always know what abilities a USB port will have.

For example, you can charge a MacBook from any of its USB ports. But a new Microsoft Surface Laptop, which has a proprietary power connector, can't be powered over USB-C. Some USB-C ports can handle HDMI video, too, but many can't.

Cables, too, are an issue. USB-C often is used for a device's charging connector, but the device may not support higher-speed USB 3 connections. They often come with cheaper USB 2 cables that are fine for charging but not for high-speed data. If you buy a new USB-C cable off Amazon, check carefully to see if it's USB 2, USB 3 or, next year, USB 4.

VESA would like to see some equivalent to nutrition labels on foods -- a standard description of what USB features a product supports that consumers can learn to look for on packaging and product websites.

"It would be neat if USB-C connectors could have a standardized label," Wiley said.

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