What is Thunderbolt 3?

What is Thunderbolt 3?

Thunderbolt 3 is set to become one of the most-used physical connectivity standards on modern-day computers, thanks to its versatile use-case, easy-to-use design, and the fact that it plays nice with other new standards, like the USB-C connection standard. That said, you might be wondering exactly what Thunderbolt 3 is and how it works.

Often, people wonder is Thunderbolt 3 USB-C, or is Thunderbolt 3 backwards compatible?  That’s exactly why we’ve put together this guide – so you can learn everything there is to know about what Thunderbolt 3 is, how Thunderbolt 3 works, and the relationship between Thunderbolt 3 and USB-C.

There are some good reasons why many computer manufacturers use Thunderbolt 3 ports instead of USB-C ports. For example, Thunderbolt 3 supports a much wider range of data transfer. Not only can Thunderbolt 3 ports transfer data at up to 40Gbps, but Thunderbolt 3 also supports high-resolution displays, and allows you to daisy-chain devices so that you only have to connect those devices to one port on your computer. USB-C usually carries data through the USB 3.1 standard (though that could change to the much more robust USB 4.0 standard soon), and USB 3.1 only supports data speeds of up to 10Gbps.

Wondering if your laptop has Thunderbolt 3 ports? While Thunderbolt 3 does use the USB-C connector, Thunderbolt 3 ports usually have a small Thunderbolt logo, which looks like a lightning bolt, near them.  If you’re considering a new computer and are wondering if it has Thunderbolt 3 ports, it’s worth checking with the manufacturer of the computer. Alternatively, you can check out a full list of Thunderbolt 3-compatible devices at this website.

What is Thunderbolt 3? How does Thunderbolt 3 work? Let’s take a deeper look.

How does Thunderbolt 3 work?

If you’re wondering how Thunderbolt 3 works, you’ve come to the right place. Thunderbolt 3 is essentially a hardware interface that is designed to combine a number of different transfer protocols into a single physical connector – ensuring that it’s versatile and easy to use.

That physical connector happens to be the USB-C connector. That’s important to keep in mind because there are some major differences between Thunderbolt 3 and USB-C. While Thunderbolt 3 is an actual data transfer protocol, USB-C is simply the type of connector that it uses. When you talk about USB-C ports, it could use a number of different protocols, including Thunderbolt 3 or USB 3.1.  Put simply, Thunderbolt 3 is backwards compatible with USB-C devices, but a USB-C computer will not work with a Thunderbolt 3 device.  For example, the Dell XPS has Thunderbolt 3 ports that can work with both Thunderbolt 3 docking stations and USB-C docking stations.  On the other hand, the Google Pixelbook has a USB-C (non-Thunderbolt 3) port and can only work with a USB-C docking station but not a Thunderbolt 3 dock.

As mentioned, Thunderbolt 3 combines a number of different standards, including PCI Express 3.0, DisplayPort 1.2 and Thunderbolt at 20GBps and 40Gbps – all in one cable. In other words, exactly how it works depends on what you use it for. Essentially the Thunderbolt 3 protocol includes a physical interface layer that can switch its mode, depending on how you want to use it. Pretty fancy, huh? What does that mean? Basically, it means you don’t have to think about exactly how the technology is working under the hood – it just works.

If you’re interested in how Thunderbolt 3 works, however, here are some more specifics. When a USB device is plugged into a Thunderbolt 3 port, it’s detected as such, and a USB controller inside your computer is activated. This controller can then route data through either the USB 2.0, 3.0, or 3.1 standards to the USB-C port (or, for all intents and purposes, the Thunderbolt 3 port). When that happens, the port is basically behaving exactly like a USB 3.1 port would.

Things work slightly differently if you plug a display into the Thunderbolt 3 port, which can be accomplished with a number of different Thunderbolt 3 display adapters. When that happens, the device is detected as a display, and the port switches to a DisplayPort mode. Then, the port is able to receive data from your graphics card or internal graphics engine, and send raw graphics data to the port to be interpreted by the display on the other end of the cable.  Because of Thunderbolt 3’s massive bandwidth, you can drive up to two 4K displays with a 60Hz refresh rate. 

One thing you’ll need to be careful with is whether your Thunderbolt 3 port supports 2 or 4 lanes.  This will determine whether your Thunderbolt 3 port supports full 40Gbps speeds (4 lanes) or 20 Gbps (2 lanes).  The mechanism behind this difference is a little convoluted but luckily our friends at GTrusted have a comprehensive list of 2 vs. 4 lane Thunderbolt 3 computers.  An example of where this is relevant is when transferring data with a Thunderbolt 3 SSD.  On a 2 lane port, you’ll only be getting 20Gbps speeds instead of the full 40.

But is Thunderbolt 3 backward compatible? Thankfully, yes. If you have the appropriate adapters, you can connect Thunderbolt 2 and original Thunderbolt devices to your computer through a Thunderbolt 3 port. Not only that, but it’s backwards compatible with other protocols too. Because it supports USB 3.1, Thunderbolt 3 also supports previous versions of USB.

Safe to say, how Thunderbolt 3 works under the hood can get a little technical – but the idea is that Thunderbolt 3 works in a range of different ways, ensuring that it’s versatile and able to work in a variety of different situations.

What is Thunderbolt 3 used for?

One of the best things about Thunderbolt 3 is that it can be used for such a wide range of applications. Remember those modes that we talked about before? Those different modes mean that you can use Thunderbolt 3 to simply transfer data from one device to another, you can use it with compatible displays, and more.

Let’s start with simple data transfer. Using an external Thunderbolt 3 device, a single Thunderbolt 3 port can transfer speeds at up to 40Gbps. To put that in perspective, an entire 4K movie can be transferred in about 30 seconds at those speeds.  As 4K video becomes ever more accessible to professional content creators and hobbyists alike, the massive speed of Thunderbolt 3 will become more and more useful.

Using Thunderbolt 3 to transfer content, however, is just the tip of the iceberg. Perhaps even cooler than that is using a Thunderbolt 3 port to connect external displays. Because of the fact that Thunderbolt 3 supports the DisplayPort 1.2 protocol, you can connect Thunderbolt 3 ports to external displays. While it uses the DisplayPort protocol, it can easily be converted into other video ports such as HDMI, DVI, or VGA through a simple adapter.   On displays that support daisy-chaining, you can even connect up to two 4K displays with a refresh rate of 60Hz through a single Thunderbolt 3 cable.

Thunderbolt 3 can transfer power too, just like USB. What that means is that laptop manufacturers can do away with those annoying propriety charging ports, and allow you to charge your laptop through Thunderbolt 3 ports instead. Considering the fact that Thunderbolt 3 allows for power transfer at up to 100W, laptops can charge pretty quickly through Thunderbolt 3 too. If you use a Thunderbolt 3 docking station, you can connect to multiple displays, transfer data, and power your laptop, all with one port. Of course, Thunderbolt 3 ports can also output power to charge your other devices too, like your phone and headphones.

With support for all these different protocols, Thunderbolt 3 can be used in a range of different situations.  What is Thunderbolt 3 used for? An example is musicians and music producers can use Thunderbolt 3 to connect audio interfaces with a number of different audio inputs and outputs. Allowing them to record multiple tracks of audio without any issues. Video producers and photographers can transfer data from an SD card at hugely fast speeds while viewing that footage on dual 4K displays. Those that need lots of ports can connect hubs to Thunderbolt 3 ports with dozens of different connectivity ports, without having to suffer from low data transfer speeds and other restrictions.

Benefits of Thunderbolt 3

Clearly, there are a dozen benefits of Thunderbolt 3. In the past, all the protocols, including DisplayPort, USB, Ethernet, and so on, used different connectors and ports.  With Thunderbolt 3, however, that changes. Your super-slim laptop only needs a few Thunderbolt 3 ports to support everything you would need to connect. Sure, you might need an adapter every now and then, but it’ll work without a hitch.

The fact that the Thunderbolt 3 standard uses the USB-C connector is handy too. Many smartphones, headphones, and other devices these days currently come with USB-C ports built into them, so using a USB-C cable, you can easily charge and transfer data between those devices. It also means that you can use your USB-C or Thunderbolt 3 cables for different things. Since Thunderbolt 3 is backwards compatible to USB, all Thunderbolt 3 cables will work as USB-C cables too. Of course, it’s important to understand that you will be limited by the bandwidth of the USB port and you won’t get Thunderbolt 3’s 40Gbps transfer rate when doing this.  If you want to live the dream of just being able to use any cable for anything, it’s worth making sure that you have high-quality Thunderbolt 3 cables. Unfortunately, Thunderbolt 3 cables are currently limited by length and you won’t find one over 2m.  Be wary of ordering bargain Thunderbolt 3 cables online, as it is a difficult cable to assemble.  A point of guidance is to only use certified Thunderbolt 3 products made by Intel-partnered companies like Cable Matters.

The USB-C connector type has other advantages too. The fact is that USB-C is a small connector type that’s also reversible. In other words, it’s a connector that can fit into smartphones and other slim devices, and it’s convenient. Unlike previous-generation USB-C connectors, you’ll be able to properly plug a USB-C connector in the first time every time.

Thunderbolt 3 is an incredibly powerful technology and makes connecting devices that little bit easier. It could soon be overshadowed too – USB 4.0 is on the way and promises Thunderbolt 3 support and a USB-C connector. Still, it might take a few years for USB 4.0 to roll out – and until then, Thunderbolt 3 is easily the most powerful and most versatile connectivity standard around.

Comments (2) -

  • Tb3 works well with a direct connect between computers of same OS, poor connectivity between macOS and win as example, why?
    • Hello,

      Thanks for the message.  The is essentially because Windows and Mac use different methods of accomplishing the connection.  Please reach out to us at support@cablematters.com if you'd like to discuss further.

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