The new Thunderbolt interface has less to do with raw speed than it does with display connectivity and better device charging. Here’s a breakdown of what you’ll get today with the updated standard.
By Mumuksh Verma
For anyone who’s used a Mac laptop in recent years, or a high-end Windows laptop, Thunderbolt 3 has probably been on your radar, and maybe it got you thinking about what it can do. This port looks like one of the new-style oval USB Type-C connectors, but it does so much more: It can carry a video signal using the DisplayPort protocol, charge connected devices, and allow data transfers at speeds beyond simple USB can manage. (See our explainer, Thunderbolt 3 vs. USB-C: What’s the difference?)
However, the history of the latest version of the Thunderbolt interface, Thunderbolt 4, begins with a change of direction. Intel has opened the Thunderbolt 3 protocol to the USB controller consortium (the USB-IF) for royalty-free use in the development of next-generation USB4, providing faster speeds and interoperability with USB4 devices. In fact, the destinations and addresses of the two new “4” specs are intertwined. (And yes, the USB team dropped the space on “USB4”. That is not a typo).
This move toward open source did not mean, however, that Intel stopped developing its traditionally proprietary Thunderbolt specification. Intel has continued to move Thunderbolt down the road, announcing Thunderbolt 4 a year ago at CES 2020, and new Thunderbolt 4-equipped PCs based on Intel 11th Generation processors (“Tiger Lake”) are beginning to roll out. These computers based on Tiger Lake also are ushering in the USB4 connectivity, so it is likely to be some confusion with Thunderbolt 4 and USB4 arriving at the same time … and sometimes, in the same real ports .
Also confusing the picture is Thunderbolt 4’s lack of a unique headline-grabbing feature, such as a faster top speed than its predecessor. Thunderbolt 4 is not a speed game; it’s more about minimum requirements than maximum speeds. To help you determine how Thunderbolt 4 differs from Thunderbolt 3, as well as USB4, we have prepared a short status overview.
Thunderbolt: a bit of history
Before we get into the specifics of the new Thunderbolt 4 protocol, let’s first make a backup and explain what Thunderbolt is and does, and how we got here.
Introduced by Intel and Apple, Thunderbolt first appeared on a MacBook Pro in 2011. The physical shape of the port was a mini DisplayPort connector with a small lightning bolt icon next to it. It combined DisplayPort and PCI Express technologies in a single cable to drive high-resolution displays and high-speed data transfers with a maximum speed of 10 Gbps. Using the same physical port, Thunderbolt 2 doubled the bandwidth to 20 Gbps and added support for DisplayPort 1.2, giving the interface the ability to transmit a video signal to a 4K display.
Thunderbolt 3 doubled the data rate, again, to 40 Gbps. Another big change: Thunderbolt 3 no longer used the mini DisplayPort connector as its physical interface, and left it in favor of the USB Type-C port, with the technology in tow on that connector, much like Thunderbolt 1 and 2 in tow. on mini DisplayPort. It also added up to 100 watts of power via USB Power Delivery (USB PD), so you can use your PC to charge your phone and other USB devices, or even charge a laptop via the port. The Thunderbolt 3 specification also introduced the Thunderbolt network with 10 Gbps Ethernet. Thunderbolt 3 provided sufficient video bandwidth that led to a wide range of applications, from single-cable cradles that could also charge your devices,
Thunderbolt 4 vs. Thunderbolt 3: What’s the difference?
Thunderbolt 4 doesn’t offer any headline-grabbing enhancements over Thunderbolt 3. On the surface, the two protocols seem very similar. They both use the physical USB Type-C connector. Both offer a maximum throughput of 40 Gbps. Both offer at least 15 watts and up to 100 watts of charging power. And they both offer support for that 10 Gbps network.
However, below the surface, Thunderbolt 4 has a number of significant advantages. For starters, it doubles the minimum video and data requirements of Thunderbolt 3. Thunderbolt 4 will support sending a video signal to two 4K displays, or to one 8K display, where Thunderbolt 3 is required to support only one 4K display. And where Thunderbolt 3 systems have to support only 16 Gbps data rate over PCI Express, Thunderbolt 4 will double that requirement to 32 Gbps. Anyone who regularly transfers giant high-resolution video files and other large data sets from storage drives to their PC for editing is sure to take advantage of that extra bandwidth.
Thunderbolt 4 will also lead to more capable peripherals. You’ll see Thunderbolt 4 docks and monitors with four Thunderbolt 4 ports – twice the two ports at most – you’ll find them on Thunderbolt 3 devices. New thin and light laptops that need less than 100 watts to charge will need to offer USB charging type C into at least one of its Thunderbolt 4 ports. And when a Thunderbolt 4 laptop is connected to a Thunderbolt 4 dock, it should be able to wake itself from sleep from a connected keyboard or mouse. Thunderbolt 4 cables will also support 40 Gbps throughput up to two meters in length, versus the maximum 0.5 meters for a passive Thunderbolt 3 cable.
With the ability to daisy chain up to six Thunderbolt devices, you have the ability to connect multiple devices without each requiring a direct connection to your computer. Combined with Thunderbolt 4’s higher charging and sleep activation capabilities and longer cables, you’ll have more flexibility in setting up your workspace so your office is less cluttered and your office life a little easier.
Thunderbolt 4 vs USB4: the key differences
Now in practice it is easy to confuse Thunderbolt 4 and USB4. They both use the USB Type-C connector. Both offer a maximum bandwidth of 40 Gbps. Both are being introduced with Intel’s new 11th Gen Core “Tiger Lake” processors. And Thunderbolt 4 is USB4 compliant, which means you can connect a USB device to your laptop’s Thunderbolt port. Thunderbolt 4 is also compatible with Thunderbolt 3. In both cases, however, the connection will default to the slower speeds of USB4 or Thunderbolt 3.
Thunderbolt 4 is basically a guarantee that you are getting the best version of USB4. While USB4 offers the same 40Gbps speed as Thunderbolt 4, there is also a slower 20Gbps version of USB4. Thunderbolt 4 also ensures that you can run at least a couple of 4K displays and transfer data at up to 32Gbps. With USB4, you are guaranteed only the bare minimum of single screen operation and a data rate of 16 Gbps. A USB4 hub also lacks the mandatory charging and wake-up requirements of Thunderbolt 4, as well as 10 Gbps networking.
Thunderbolt 4 vs USB4: The Basics
USB4 does have an advantage over Thunderbolt 4: logos that are more informative. With USB4, you should see the “USB 20Gbps” and “USB 40Gbps” logos next to the USB Type-C ports that will tell you what type of USB4 you are dealing with. Unfortunately, Intel doesn’t offer such details with its Thunderbolt logos. A Thunderbolt logo is a Thunderbolt logo is lightning, with no way of knowing just by looking at the side of your laptop or at the I / O panel of your desktop PC if a port is version 1, 2, 3 or Thunderbolt 4. (The connector will tell you if it’s Thunderbolt 1 or 2 versus Thunderbolt 3 or 4, but that’s all you can assume on the face of it.) You will need to consult your user manual or spec sheet to find out which version of Thunderbolt a device offers. .Thunderbolt 4 cables may include a “4” next to the Thunderbolt 4 logo, but this specificity is rarely offered on laptops).
Security against Thunderspy
One final advantage that Thunderbolt 4 offers over Thunderbolt 3 is better security against Thunderspy attacks. In such a potential attack, a hacker can steal your data through the vulnerabilities of a Thunderbolt port. Such an attack requires physical access to your device, but it takes five minutes and is effective even when your laptop is locked or asleep, or your hard drive is encrypted.
A Thunderspy attack can work by taking advantage of the PCI Express portion of Thunderbolt and its direct memory access (DMA), which bypasses the CPU to allow fast access to system memory. Thunderbolt 4 requires Intel Virtualization Technology for Directed I / O (VT-d), which protects against DMA attacks.
How it works: VT-d offers DMA remapping, which isolates a portion of the system memory for a connected device so that the device cannot read or write to other areas of its memory. Basically, you lock a part of the system memory for a Thunderbolt device, so you cannot access other places in memory to overwrite, for example, your device’s password protection.
Without a doubt, this vulnerability is a very remote threat to most people. It is primarily a concern for corporate laptops that can travel a lot, stay in unsecured locations, and contain extremely sensitive business or financial data.
Arrival of Thunderbolt 4: Rolling Thunder
Thunderbolt 4 laptops based on Intel’s 11th generation Core “Tiger Lake” processors are just now starting to roll out. We saw the first Tiger Lake laptops with Thunderbolt 4 support last fall in the latest versions of the Asus ZenBook 13 (UX325EA) and Dell XPS 13 (9310). More are sure to come, but not all Tiger Lake laptops with USB-C ports will offer Thunderbolt 4 support. Look at the spec sheets carefully, as well as the Thunderbolt logo, because without it you are probably looking at a standard USB4 port, which offers previous generation Thunderbolt 3 capabilities.
Apple’s new MacBook Air, MacBook Pro, and Mac mini M1 were released in late 2020, and while these new systems feature USB4 ports, they don’t offer formal Thunderbolt 4 support (Thunderbolt 3 only). It remains to be seen when the first Mac with Thunderbolt 4 will arrive and if it will appear on a Mac with Apple’s own M1 silicon or on a Mac based on Intel Tiger Lake CPUs.
On the peripheral side of the fence, the first Thunderbolt 4 docks were starting to hit the market with announcements at CES 2021 (see this example from Kensington and another from OWC), while hubs, external drives, external GPUs and displays seem imminent. . You can be sure they will start rolling out later this year as more Thunderbolt 4 PCs and laptops are released.