The new USB 4 standard will have three main benefits over prior versions of USB.
- 40 Gbps Maximum Speed: By using two-lane cables, some devices will be able to operate at up to 40 Gbps, the same speed as Thunderbolt 3.
- Compatible with Thunderbolt 3 devices: Some, but not necessarily all USB 4 implementations will also work with Thunderbolt 3 devices.
- Better Resource Allocation for Video: If you’re using a USB 4 port to transport both video and data at the same time, the port will allocate bandwidth accordingly. So, if the video only needs 20 percent of the bandwidth to drive your 1080p monitor that’s also a hub, the other 80 percent will be free for transferring files from your external SSD.
Benefits of USB 4.0
- USB 4.0 is backwards compatible with USB type a to c
- We can connect multiple devices with the same USB 4.0 connector
- USB 4.0 support Intel Thunderbolt technology
- USB 4.0 will be much cheaper than USB 3.0 because thunderbolt technology is now open source.
- USB 4.0 can support up to 100 watts of power usage.
- USB 4.0 can consume less power than USB 3.0 connector
Will Use Type-C Ports
This almost goes without saying: USB 4 will only operate over the Type-C connector. Don’t expect to see a USB 4 device or hub with old-fashioned Type-A ports.
That’s no surprise, as other recent standards such as USB Power Delivery only work on Type-C.
If you do connect to, for example, a Type-A 3.1 port by using an adapter, the speed and power will drop down to the lowest common denominator.
Compatible With Thunderbolt 3, Sort-Of
Intel made news when it said it had given the Thunderbolt 3 protocol to USB Promoter Group, allowing devices with USB 4 ports to potentially be compatible with Thunderbolt 3 devices and USB 4 devices to attach to Thunderbolt 3.
That’s good news for everyone, especially laptop users who want to play games by connecting an eGPU (external graphics card).
Though there are a number of Thunderbolt 3 eGPUs out there, few laptops and desktops come with Thunderbolt 3 and almost no motherboards support Thunderbolt 3 out of the box. Because Thunderbolt is an Intel standard, you won’t find it on any AMD-powered computer. Thunderbolt 3 is also more expensive to implement than standard USB, because it’s not an open standard and it requires an extra chip. So today, if you want an eGPU or a super-speedy Thunderbolt 3 storage drive, your choice of computer is very limited.
With USB 4, device and host manufacturers won’t have to pay Intel any royalties so there’s a much better chance of mass adoption. However, there’s a catch: Thunderbolt compatibility is not a required part of the USB 4 spec so manufacturers don’t have to implement it.
You could end up buying a laptop with USB 4 and find that it doesn’t work with, say, your Razer Core X graphics dock. However, USB Promoter Group CEO Brad Saunders anticipates that most PCs with USB 4 will be made to work with Thunderbolt 3.
“We do expect PC vendors to broadly support Thunderbolt backward compatibility, because most of what they need is already built into the USB 4 design,” Saunders said. “It’s based on the same technology so we do anticipate a high rate of adoption there, but the phone guys will probably choose not to add the extra little bit they need to be backward compatible.”
Though Saunders is optimistic about PC manufacturers adding Thunderbolt 3 compatibility to their USB 4 ports, we should note that any device which wants to market itself as Thunderbolt 3 compatible will probably need to be certified by Intel. Today, any Thunderbolt 3 product has to undergo a rigorous validation process that costs money.
Three Speeds of USB 4
Though it can hit theoretical speeds of up to 40 Gbps, not all USB devices or hosts will support that standard. Saunders told us that there will be three speeds: 10 Gbps, 20 Gbps and 40 Gbps. Expect smaller and less-expensive devices such as phones and Chromebooks to use one of the lower speeds and, when you do get a laptop, you’ll need to make sure to look at the specs if you want the fastest USB 4 connection available.
Great at Sharing Bandwidth Between Video and Data
A big part of the USB 4 spec is the ability to dynamically adjust the amount of resources that are available when you are sending both video and data over the same connection. So, let’s say that you have USB 4 with a 40 Gbps maximum and you’re outputting to a 4K monitor while copying a ton of files from an external SSD. And let’s stipulate that the video feed needs about 12.5 Gbps. In that case, USB 4 would allocate the remaining 27.5 Mbps to your backup drive.
USB-C introduced “alternative mode,” the ability to transmit DisplayPort / HDMI video from a Type-C port, but the current 3.x spec doesn’t provide a good way to split up resources. According to Saunders, DisplayPort alt mode can split the bandwidth between USB data and video data exactly 50/50, and HDMI alt mode doesn’t allow simultaneous USB data at all.
“With USB SuperSpeed, we didn’t have quite the flexibility in architecture to really manage those two distinct bandwidths [data and video] in a combined fashion over the connector,” Saunders said. “So this is really optimized for more scalability between the different application types.”
Rather than using alternative mode, many current docking stations use DisplayLink technology, which compresses the video signal and turns it into USB data. It will be interesting to see whether most USB 4 docks use alternative mode instead.
All USB 4 Hosts Support USB PD
Where some current-day USB Type-C devices support the USB Power Delivery (USB PD) standard for carrying electricity to high-powered devices, not all of them do. Every USB 4 device and host will have to comply with USB PD, which allows for higher wattages and better power management.
USB PD can theoretically provide up to 100 watts, but charging devices do not have to support that amount of power. So there’s no guarantee that a given USB 4 port would give or take the amount that a particular notebook requires to operate, but you can expect it to follow the spec.
Backward Compatible With Older Device
The best thing about all generations of USB is how well they work together. USB 4 will work with USB 3 and USB 2 devices and ports. It should go without saying, though, that you’ll only get the speed and capabilities of the weakest part of your connection. A USB 4 device won’t be able to transfer at 40 Gbps when you hook it to a USB 3.2 port and an old-school USB 2 port won’t suddenly get faster just because you connect it to a brand new USB 4 backup drive.
| Specification | Throughput | Previous Term | Technical Term | Marketing Term |
| USB 4 | 40 Gbps | N/A | USB 4.0 | Not Announced |
| USB 3.2 | 20 Gbps | N/A | USB 3.2 Gen 2×2 | SuperSpeed USB 20Gbps |
| USB 3.1 | 10 Gbps | USB 3.1 Gen 2 | USB 3.2 Gen 2 | SuperSpeed USB 10Gbps |
| USB 3.0 | 5 Gbps | USB 3.1 Gen 1 | USB 3.2 Gen 1 | SuperSpeed USB |
When it will be available?
We can expect the USB 4 spec devices will be available by 2020, to note still the latest current standard, USB 3.2, was not yet widely adopted.
Brad Saunders said to Tom’s Hardware, that “we don’t plan to get into a 4.0, 4.1, 4.2 kinds of the iterative path,” he said. “When and if it goes faster, we’ll simply have the faster version of the certification and the brand.”
