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Thunderbolt 4: Everything you need to know

Intel Thunderbolt 4
Intel Thunderbolt 4 (Image credit: Intel)

What you need to know

  • Intel has detailed Thunderbolt 4, and the new standard has 40Gb/s bandwidth and USB4 integration.
  • Changes to the controller sees three downstream ports, allowing you to use more accessories with the standard.
  • Thunderbolt 4 also has 100W USB PD charging, and outgoing charge up to 15W for charging other devices.

Intel made several key changes to Thunderbolt technology over the last three years to make it more mainstream. It provided the specification for Thunderbolt 3 to the USB Implementers Forum (USB-IF), allowing Thunderbolt to become universally compatible with USB. Thunderbolt 3 forms the backbone of USB4, and that's one of the reasons USB4 has 40Gb/s bandwidth — double that of USB 3.2.

Intel is now introducing Thunderbolt 4, with the new standard offering a few key features. The bandwidth with Thunderbolt 4 is unchanged at 40Gb/s, but Intel is introducing new controllers that introduce three downstream ports that will share the bandwidth, making it that much easier to connect more accessories. This is a big deal for Thunderbolt docks, because they will be able to offer more ports.

Intel is also adding support for two 4K monitors or one 8K panel, and the latter is new with Thunderbolt 4. For context, Thunderbolt 3 could drive up to a 5K monitor, but with 8K displays on the horizon, Intel is making sure its latest spec can handle the extra bandwidth.

Thunderbolt 4 USB

Source: Intel (Image credit: Source: Intel)

Because of its universal compatibility, Thunderbolt 4 works with all older generations of USB devices, and the standard uses a USB-C to C cable, making things that much easier for accessory makers to integrate Thunderbolt 4 into their designs.

Intel isn't making a lot of changes here in terms of branding and visibility: Thunderbolt 4 retains the same logo and branding as Thunderbolt 3, with a numeral 4 on the cable itself signifying the new standard. On the subject of cables, Intel is also rolling out 2 meter cables with Thunderbolt 4, making it just a little bit easier to use the port for things like charging phones.

Thunderbolt vs USB

Source: Intel (Image credit: Source: Intel)

Intel is also adding Direct Memory Access protection for vendors to get certification for Thunderbolt 4, and Intel's slide deck from the briefing mentions that it needs Intel VT-d tech. Intel has clarified that Thunderbolt certification will be available for machines that do not feature Intel silicon, so for now, we'll have to wait and see how DMA protection will be implemented by other vendors.

With USB the ubiquitous standard for PCs, Intel is looking to Thunderbolt 4 to get more mainstream vendors to add the port to their designs. Intel requires that device vendors add at least one charging port to the downstream ports with Thunderbolt 4, so you should be able to charge your notebook and other devices via Thunderbolt 4.

The standard leverages USB PD, and it can handle an incoming charge of 100W, provided the device in question needs a 100W charge. As for outgoing charge via the Thunderbolt 4 port — for charging your phone or other accessories — the standard goes up to 15W.

Thunderbolt 4 accessories

Source: Intel (Image credit: Source: Intel)

The first set of Thunderbolt 4 device controllers based on Intel's 8000 series — the JHL8540 and JHL8340 — will be debuting in the market sometime later this year, as well a device controller that will allow accessory makers to include three downstream Thunderbolt ports.

Intel integrated Thunderbolt 3 into Ice Lake designs, and the vendor says the upcoming Tiger Lake chips will be the first to offer Thunderbolt 4 out of the box. These designs are slated to debut in the coming months, so we should be hearing more soon.

  • I suspect the unremarked upon "Required Intel VT-d based DMA protection" is the real news here. Hopefully, this addition to the specification addresses the hardware security concerns that Microsoft (and others) have had with Thunderbolt.
  • I was thinking the same thing. It'd be nice to see Microsoft finally embrace Thunderbolt. I honestly always thought their security concerns were BS because all of the Thunderbolt 3 vulnerabilities required physical access to the device. While it's understandable that they wanted to avoid more vulnerabilities, the professional consensus is that once an attacker has physical access it's pretty much game over regardless of whether the device has Thunderbolt or not.
  • I doubt security was the real reason they never included it. Microsoft was more interested in locking people into an expensive proprietary accessory ecosystem with Surface. It’s a shame, it kept me far away from Surface. My company, and all of my customers use TB3 docks, so not having it is a deal breaker for business use. I don’t see Microsoft ever embracing USB4 or Thunderbolt 4. They want to sell overpriced docks more than give their customers what they need.
  • MS is the opposite of locking people into an ecosystem. PC has always been about universal standards, to a fault. That distinction is how Apple made their comeback offering simplicity and security (with their walled garden MO). Regarding the Surface proprietary connector, it also has always had a USB port so a Surface could do anything any other PC could do. I guess the only thing you don't like was the radical look of the charging cable but every PC brand has their own charging cables that aren't necessarily interchangeable either. Further, HP has it's own proprietary docking stations on their business lines that also aren't interchangeable. I'm sure most vendors do. You can choose to use them or not. As I understand it, the reason MS didn't embrace Thunderbolt was because Intel charges a license fee which drives up cost and most average users don't care enough about the advantages to justify the price increase. I thought I read somewhere that Intel will no longer charge a license fee for Thunderbolt 4. If so, I'm sure MS will finally incorporate it.
  • Unless MS can be sure TB4 works on ARM, AMD, and Intel devices (assuming they end up making more Surface devices running AMD hardware in the future), they probably won't. When they're sure that port functionality is consistent across the entire line-up, then they'll support it.
  • TB4 is an open standard and the main people who want it buy Intel Surface Books.
  • I was about uniformity, not their proprietary port. If all they cares about was Surface Connect, they could have never included mini-DisplayPort on the SB1, and they could have avoided USB-C altogether. Looking at the first USB-C device (SB2), the processor didn't have enough PCIe lanes to support TB3 on any of the models with a built-in GPU (initially, I believe it was only one SKU of the 13" that did not carry a GPU). Then, with later Surface models, they all started getting USB-C. If they had released some models with TB3 and others without, it would have been hell to deal with at the enterprise level. Not to mention their WoARM plans.
  • That's...not actually the security consensus. If it were, then local passwords would also be considered useless because "once you have access to the hardware it's game over." Security is a layered implementation, and Microsoft (and others) have taken steps to mitigate attacks both physical and remote. For local access - - Secure ports (TB is a vulnerability there due to direct access to the PCIe bus)
    - Secure boot
    - Bitlocker
    - Native drive encryption (on some SSD's)
    - Local account security or domain/MS account
    - Biometrics (Windows Hello)
    - Least privileged access (not running everyone as admin)
    - Various OS technologies such as ASLR and DEP Yes, if you have physical access to a device you have more surfaces to attack, however it is not automatically 'game over' and by placing as many barriers as possible you increase the time required for the attack and the number of vulnerabilities needed to pull it off. These are valuable, it's rare that an attacker has unlimited time and a zero day for every required layer.
  • Editors, please fix: Lower case b = bit. Capital B = Byte or 8*bit. The spec is 40Gb/s not 40GB/s. 40GB/s implies that it's 8x faster than it actually is.
  • You are assuming there is an editor here.
  • Nice unnecessary comment
  • Whereas yours was necessary?
  • My mistake there. Fixed it now. Thanks!
  • But don't you wish it was true though?
  • Assuming one has an adapter that allows one to plug a USB3-C device into an earlier USB2/3 port, would this allow a Thunderbolt 4 device to be connected to an older laptop, albeit at the much lower data transmission rate? In other words, is a Thunderbolt 4 device going to communicate with an older USB2 or USB3 port?
  • No, Thunderbolt is basically external PCI-express over a USB-C connector, they only share the plug through the USB-C Alternate Mode, but their protocols are completely different. USB-C connectors can carry extra signals such as HDMI, DisplayPort, MHL, VirtualLink, Thunderbolt, .... Only USB devices are backward compatible and work when plugged into a USB-A port. Even when connected to a USB-C port, a device that requires one of the other signals will not work if that specific port doesn't provide the proper Alternate Mode. Some devices provide flexibility by supporting several modes, such as ASUS ZenScreen MB16AC and MB16AMT monitors that basically take advantage of DisplayPort Alt-mode, but fallback to USB-only DisplayLink, at the expense of refresh rate, if the port doesn't support the specific signal.
    Unfortunately, Thunderbolt devices are working at a lower level, and providing a USB-only fallback would greatly increases their complexity and cost, while negating their performances benefits, so don't expect it.
  • The only port you'll need. Again.
  • Exactly. Haven’t we heard this before?
  • Big fat meh. Yes, a subset of creators with high performance needs will use this and the expensive peripherals needed to take advantage, but the consumer base at large won't. Think about it, really the only consumer forward use is the eGPU (everything else can and is supported in USB-C to a great degree), and not many consumers use eGPU. This is just like eSATA, Firewire, and the like, higher performance that the average consumer doesn't need for the premium cost.
  • I don't think the goal is to replace USB peripherals. Replacing desktop computers by laptops limits extensibility, while Thunderbolt could enable you to have a laptop computer and a desktop expansion mini-tower that supports a few PCI-express slots (not just a GPU, it could support NVMe SSD, ...). Instead of replacing USB peripherals, it could completely replace proprietary docks.
    It could also enable designs like the Surface Book that required a special PCIe design for the GPU but could simply base its clipboard and keyboard connection on Thunderbolt.