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What is USB4? Plus, List of the Best USB 4 Cables

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What is USB4

In this article, we explain what is USB4. If you are looking to invest in the new standard, read along.

The USB standard is omnipresent in the entire tech world. USB (Universal Serial Bus) standard has observed its significant share of updates across the past 23 years right from its inception. Each USB standard brought new features, higher speeds, and new connection types.

Related: Comparing USB-C vs. Thunderbolt 3 Specs

Looking back into history, the USB standard was adopted in 1996 to normalize peripheral connections within one specification. The first USB specification is the USB 1.0.

It utilized the well-known Type-A connection on the host and provided transfer speeds reaching up to 12 Mbps. In  April 2000, USB 2.0 was introduced, and it was pretty faster, working at up to 480 Mbps.

USB 2.0 adopted new form factors encompassing the Micro B port, typically observed on external hard drives and older phones. In November 2008, USB 3.0 was introduced with a further boost in speed. It provided up to 5 Gbps transfer speeds.

Also Read: How do I Check USB-C capabilities?

Iterations of USB 3.0 were USB 3.1 in 2014 (provided up to 10 Gbps) and USB 3.2 in 2017 (provided up to 20 Gbps). USB 3.0 speeds supported multiple connector types like the standard A connector, B, micro-B, and Type-C connection.

USB4 was first announced in 2019. It appears in specific modern computers, including Apple’s latest M1-powered iMacs, its M1-based Macbooks, and Mac Mini and laptops like Intel 11th Gen Tiger Lake laptops.

There are a few USB 4 devices in the market. However, a new generation of USB4-powered docks and peripherals is releasing out.

After being officially announced by the USB Promoter Group on 4th March 2019, the USB4 cables and devices are now available.

The question now arises –what is USB4? This article discusses what’s the new specification provides and shows its benefits compared to the existing USB 3.2 standard.

Key benefits of USB4:

The USB4 specification (formally recognized as “USB4,” written without space) comes with three important traits, as per the USB Implementers Forum (USB-IF). The same may include:

  1. Two-lane operation with speeds up to 40 Gbps operation (compared to certified cables), utilizing the USB Type-C connection;
  2. More competent sharing between data and display protocols;
  3. Backward compatibility with USB 3.2, USB 3.1, USB 3.0, USB 2.0, and Thunderbolt 3.

Let’s go through in-depth details of the benefits of USB4:

1. Remarkably faster transfer speeds than USB 3.2:

This is the most apparent benefit of USB4. Presently known as the quickest USB specification, the USB 3.2 Gen 2×2 only provides transfer speeds up to 20 Gbps, although its 10 Gbps counterpart is more common on devices.

The data transfer speeds of USB 3.2 Gen 2 are up to 10 Gbps, and USB 3.2 Gen 1 (along with all previous USB 3.0 and 3.1 specifications) run at up to 5 Gbps. The latest standard USB4 can transfer data at speed up to 40 Gbps, equivalent to Thunderbolt 3, the present sovereign of data transfer rates.

Similar to Thunderbolt 3, USB4 would adopt the USB Type-C connection. Essentially, USB Type-C is the reversible connection observed on most contemporary Android phones and laptops that we see today.

The USB Type-C construction also facilitates display connections that perform well into USB4’s second trait, i.e., dynamic bandwidth allocation for data and display connections.

USB Standard Lanes Speed Maximum Length
USB 3.1 Gen 1 1 5 Gbps 2m
USB 3.1 Gen 2 1 10 Gbps 1m
USB 3.2 Gen 1 1 5 Gbps 2m
USB 3.2 Gen 2 1 10 Gbps 1m
USB 3.2 Gen 1×2 2 10 Gbps 2m
USB 3.2 Gen 2×2 2 20 Gbps 1m
USB4 Gen 2 1 10 Gbps 1m
USB4 Gen 2×2 2 20 Gbps 1m
USB4 Gen 3 1 20 Gbps 0.8m
USB4 Gen 3×2 2 40 Gbps 0.8m

2. Improved bandwidth allocation over USB Type-C:

Though other USB specifications can identically transfer data and display info, usually, they face issues with bandwidth allocation and bandwidth splitting uniformly amongst connected devices.

For instance, if an external storage device and a display are connected to a PC via a USB Type-C dock, the bandwidth will be uniformly allocated amongst the display and a storage device. The same can stifle the transfer rate of the particular storage device.

USB4 doesn’t pose such concerns since it would now be capable of dynamically supervising bandwidth requirements for the connected displays and then saving the remaining bandwidth for data transfer.

Formerly, data could only be transmitted via the data lane, and the video can only be transferred through the video lane.

This implies that although a connected display doesn’t use the whole lane’s bandwidth value (like 5 Gbps or 10Gbps), the idle bandwidth cannot be assigned for data transfer and vice versa. USB4 facilitates sharing of lanes by video and data.

Thus, they can share the total maximum bandwidth. Consequently, it increases the connection efficiency of multiple devices via a dock.

3. Backward compatible with USB 2.0 and up:

The inception of the Type-C connector has increased anxiety among many customers. The USB-IF is familiar with this. So, with the intent not to instantly make other USB specifications outdated, USB4 would offer backward compatibility with standards ranging from USB 2.0 to the cutting-edge USB 3.2 Gen 2×2 specifications. USB 4.0 can work with the older USB standards like external disks, mice, keyboards, etc.

Also, it is compatible with USB 2.0 and USB 3.0. You can connect a USB 2.0 external HDD to a USB4 port, although you have reserved this drive for backups. To let it work effectively, you must traverse from USB Type-A to USB Type-C with the assistance of a USB adapter.

Although there is a tiny catch, this is excellent news to users with inherited USB peripherals. Though obsolete USB devices can connect to a USB4 port (through an adapter, if required), the device would only be capable of running at the slower USB standard.

For instance, to better understand this, a USB 2.0 external HDD can connect to a USB4 port through an adapter. However, the transfer will only occur at USB 2.0 speeds (i.e., up to 480 Mbps).

4. Improved Resource Allocation for Video, PCIe:

In substitute for an alternative model where the other interface gains the upper hand on the connection, the USB 4 devices can adopt a process known as “protocol tunneling.”

This process transmits PCIe, DisplayPort, and USB packets simultaneously while distributing bandwidth consequently.

Hence, if the video only demands 20% of the bandwidth to power your 1080p monitor, a hub, the remaining 80% will be reserved for transferring files from your external SDD that can operate on either PCIe or USB protocol.

USB4 vs. Thunderbolt 3 vs. Thunderbolt 4:

The USB-IF mentioned that USB4 would offer backward compatibility with Thunderbolt 3. However, you need to note a few points. You must comprehend that the USB4 spec is dependent on the Thunderbolt 3 protocol that Intel contributed to the USB.

Although it is based on the TB3 protocol, the support for TB3 is not compulsory for USB4. Essentially, USB4 devices must be separately verified by Intel as “Thunderbolt 4 certified” to utilize the Thunderbolt logo. Those USB4 ports which are Thunderbolt 3 compatible will then be called Thunderbolt 4 ports.

It implies that not every PC with USB4 would be compatible with Thunderbolt 3 as well as Thunderbolt 4 peripherals.

It is implausible that Thunderbolt 3 will vanish from the PC setting. Though it’s expected that we will observe USB4 desktops and laptops to be released with AMD CPUs, it is unsure whether these devices will be compatible with Thunderbolt 3/4 or not.

This is because they need to obtain distinct Intel certifications. Conversely, it is expected that Intel-powered devices with USB4 have higher probabilities of being compatible with Thunderbolt 3. The reason is they are already equipped with Intel technology. USB4 supports Thunderbolt 3, but it is not mandatory.

Consumers should explicitly note whether a new device supports Thunderbolt 3 through USB4 or not if they wish to connect it to it through Thunderbolt 3.

Other benefits of using USB4:

Apart from providing higher transfer speeds, backward compatibility, and enhanced bandwidth allocation, USB4 would also provide Power Delivery at up to 100W.

This is because it uses the USB-C port. Before the release of USB4, several USB-C ports already supported this. However, Power Delivery might be universally available with USB4, although not at 100W every time.

Although few newer devices (chiefly laptops) equipped with a USB Type-C port can be charged through that connection, all of them can’t. This can arouse confusion among customers.

When employed by the host, USB4 will also adopt intelligent Power Delivery. This would enable a USB4 cable to convey power equivalent to what is requested by a connected device (up to 100 Watts). Power Delivery over USB4 is bi-directional, so it allows power to be transmitted and received from a connected device.

Where to buy USB4 cables?

Gradually, USB4 cables are now seen in the market. You must purchase a quality USB4 cable from a reliable brand. Cable Matters provides superior quality USB4 cables (with speeds up to 40 Gbps) as well as Thunderbolt 4 cables which are fully compatible with USB4.

Here is the list of some of the best USB4 cables, along with purchase links:

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