The new Thunderbolt interface is more concerned with display connection and device charging than with sheer performance. Here's a rundown of what the new standard will net you today.
Anyone who has used a Mac laptop or a high-end Windows notebook in recent years has certainly heard about Thunderbolt 3—and may have been perplexed by what it can achieve. This port resembles one of the new oval USB Type-C connections, however, it accomplishes a lot more: It can transmit a visual signal via the DisplayPort protocol, charge connected devices, and transfer data at speeds faster than USB. (For further information, see Thunderbolt 3 vs. USB-C: What's the Difference?)
However, the narrative of the latest Thunderbolt interface—Thunderbolt 4—begins with a shift in focus. The Thunderbolt 3 protocol was made available to USB's regulating consortium (the USB-IF) for royalty-free usage in the development of the next-generation USB4, resulting in better speeds and compatibility for USB4 devices. The destinies and trajectories of the two new "4" standards are indeed interwoven. (Yes, the USB team omitted the space in "USB4". That is not a mistake.)
This shift toward open source did not, however, mean that Intel abandoned its typically private Thunderbolt specification. Intel has kept Thunderbolt going forward, announcing Thunderbolt 4 at CES 2020 a year ago, and new Thunderbolt 4-equipped PCs based on Intel's 11th Generation ("Tiger Lake") Core CPUs are only now beginning to appear. With Thunderbolt 4 and USB4 both arriving at the same time...and often on the same real ports...these Tiger Lake-based machines are likely to cause some confusion.
Thunderbolt 4's absence of a single headline-grabbing feature, such as a quicker top-end speed than its predecessor, further complicates matters. Thunderbolt 4 is not a speed play; rather, it is concerned with minimum needs rather than maximum speeds. We've put up a quick primer on Thunderbolt 4 to help you understand how it varies from Thunderbolt 3 and USB4.
Thunderbolt: A Narrative Structure
Before we dive into the mechanics of the new Thunderbolt 4 protocol, let's go through what Thunderbolt is and what it accomplishes, as well as how we got here.
Thunderbolt was first seen on a MacBook Pro in 2011, thanks to Intel and Apple. The port's physical shape was a tiny DisplayPort connection with a lightning-strike emblem next to it. It merged DisplayPort and PCI Express technologies in a single connection to operate high-resolution screens, as well as high-speed data, transfers up to 10Gbps. Thunderbolt 2 increased the speed to 20Gbps and introduced DisplayPort 1.2 capability, allowing the interface to transport a video stream to a 4K monitor using the same physical connector.
Thunderbolt 1–4: The Essentials
Thunderbolt 3 more than doubles the data throughput to 40Gbps. Another significant difference is that Thunderbolt 3 no longer uses the small DisplayPort connector as its physical interface, instead opting for the USB Type-C port, with the technology piggybacking on that connector in the same manner as Thunderbolt 1 and 2 did. It also provided up to 100 watts of electricity through USB Power Delivery (USB PD), allowing you to charge your phone and other USB devices from your PC—or even charge a laptop through the connection. Thunderbolt networking with 10Gbps Ethernet was also featured in the Thunderbolt 3 specification. Thunderbolt 3 supplied enough video bandwidth to enable a broad range of applications, including single-cable docks that could also charge your devices and external GPUs to boost a laptop's graphics capabilities.
What Is the Difference Between Thunderbolt 4 and Thunderbolt 3?
Thunderbolt 4 does not provide any notable enhancements over Thunderbolt 3. The two methods appear to be extremely similar on the surface. Both use the actual USB Type-C connection. Both have a top throughput of 40Gbps. Both provide at least 15 watts of charging power and up to 100 watts. And both provide 10Gbps networking capability.
Thunderbolt 4 has a number of significant advantages beneath the surface. For starters, it doubles Thunderbolt 3's minimum video and data needs. Thunderbolt 4 will be able to send video signals to two 4K displays or one 8K display, whereas Thunderbolt 3 is limited to a single 4K display. Thunderbolt 3 systems must only handle a 16Gbps data rate over PCI Express; Thunderbolt 4 will quadruple that requirement to 32Gbps. Anyone who often uploads massive quantities of high-resolution video and other huge data sets from storage devices to their PC for editing would undoubtedly benefit from the increased bandwidth.
Thunderbolt 4 will also result in more powerful peripherals. Thunderbolt 4 docks and monitors will include four Thunderbolt 4 ports, which is double the two ports seen on Thunderbolt 3 products. New thin-and-light laptops that require less than 100 watts to charge must include USB Type-C charging on at least one Thunderbolt 4 connector. When a Thunderbolt 4 laptop is docked, it must be able to rouse from sleep using a linked keyboard or mouse. Thunderbolt 4 cables will also offer 40Gbps speed at up to two meters in length, compared to a passive Thunderbolt 3 cable's limit of 0.5 meters.
With the ability to daisy-chain up to six Thunderbolt devices, you may connect many devices without requiring each one to have a direct connection to your computer. With Thunderbolt 4's increased charging and wake-from-sleep capabilities, as well as longer cables, you'll have more choice in setting up your workstation, making your office less wire-cluttered and your office life a little simpler.
The Key Differences Between Thunderbolt 4 and USB4
In practice, it's simple to mix up Thunderbolt 4 with USB4. Both make use of the USB Type-C connection. They have a combined maximum bandwidth of 40Gbps. They're both powered by Intel's latest 11th Generation "Tiger Lake" Core CPUs. And because Thunderbolt 4 supports USB4, you may attach a USB device to your laptop's Thunderbolt port. Thunderbolt 3 and Thunderbolt 4 are also backward compatible. However, in all cases, the connection will default to the slower speeds of USB4 or Thunderbolt 3.
Thunderbolt 4 is essentially an assurance that you are receiving the finest USB4 version. While USB4 has the same 40Gbps speed as Thunderbolt 4, it also has a slower 20Gbps version. Thunderbolt 4 also ensures that you can operate at least two 4K monitors and transport data at up to 32Gbps. With USB4, you can only run a single monitor and transfer data at a bandwidth of 16Gbps. A USB4 hub also lacks Thunderbolt 4's necessary charging and wake-from-sleep requirements, as well as 10Gbps networking.
Thunderbolt 4 vs. USB4: The Fundamentals
USB4 does offer one benefit over Thunderbolt 4: more descriptive branding. When it comes to USB4, you should notice "USB 20Gbps" and "USB 40Gbps" labels next to USB Type-C ports to indicate which flavor of USB4 you have. Unfortunately, Intel does not include such information with its Thunderbolt branding. A Thunderbolt logo is a lightning bolt, and there's no way to identify whether a port is Thunderbolt version 1, 2, 3, or 4 by looking at the side of your laptop or desktop PC's I/O panel. (The connector will inform you if it's Thunderbolt 1 or 2, or Thunderbolt 3 or 4, but that's all you can tell from the outside.) To find out which Thunderbolt version a device supports, examine the user manual or spec sheet. (Some Thunderbolt 4 cables may include a "4" next to the Thunderbolt 4 emblem, however, this level of detail is not normally available on laptops.)
Protection Against Thunderspy
Another advantage of Thunderbolt 4 over Thunderbolt 3 is improved protection against Thunderspy attacks. In such an assault, a hacker might take your data by exploiting flaws in a Thunderbolt port. This type of attack involves physical access to your device, yet it just takes five minutes and works even if your laptop is locked or asleep, or your hard drive is encrypted.
Thunderspy attacks are able to operate by using Thunderbolt's PCI Express component and its direct memory access (DMA), which bypasses the CPU to provide quick access to system memory. Thunderbolt 4 needs Intel's Virtualization Technology for Directed I/O (VT-d), which provides DMA protection.
This is how it works: DMA remapping is a feature of VT-d that isolates a piece of system memory for a connected device, preventing the device from reading or writing to other areas of your memory. It basically blocks access to a section of system memory for a Thunderbolt device, so it can't erase, for example, your device's password security.
To be clear, most people are not at risk from this susceptibility. It's primarily a concern for corporate laptops, which may travel frequently, be left in unsecured locations, and contain highly sensitive financial or other business data.
The Arrival of Thunderbolt 4: Rolling Thunder
Thunderbolt 4 laptops powered by Intel's 11th Generation "Tiger Lake" Core CPUs are only now becoming available. Last autumn, we saw the first Tiger Lake laptops with Thunderbolt 4 connectivity in the newest Asus ZenBook 13 (UX325EA) and Dell XPS 13 models (9310). More will undoubtedly arrive, but not every Tiger Lake laptop with USB-C ports will enable Thunderbolt 4. Examine the spec papers carefully, as well as the Thunderbolt logo, since if you don't see it, you're probably looking at a vanilla USB4 port with previous-generation Thunderbolt 3 capabilities.
While Apple's new M1 MacBook Air, MacBook Pro, and Mac mini have USB4 connectors, they do not have certified Thunderbolt 4 capability (just Thunderbolt 3). It remains to be seen when the first Thunderbolt 4 Mac will be released, and whether it will be on a Mac powered by Apple's own M1 silicon or a Mac powered by Intel Tiger Lake CPUs.
On the periphery, the first Thunderbolt 4 docks were beginning to enter the market with announcements at CES 2021 (see this example from Kensington(Opens in a new window) and another from OWC(Opens in a new window)), while hubs, external drives, external GPUs, and displays appear to be on the way. You can bet they'll start appearing later this year when more Thunderbolt 4 PCs and laptops are introduced.
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