What is Thunderbolt 3? Here’s everything you need to know

Peripheral cables are hard enough to keep track of without cutesy terms like “Thunderbolt” and nonsense names like “Type C.” Thunderbolt 3 — the newest version of Intel’s connection tech — may be particularly confusing, having gone through several different phases since making the jump from Apple products to mainstream laptops and desktops.

Knowing the difference between these two technologies is important, especially when you’re thinking about which computer is right for you. Don’t be surprised if you look at a new laptop and see nothing but “USB-C” and “Thunderbolt” advertised in the specifications. It’s the new norm.

What exactly is all this jargon? Let’s take a look!

The Thunderbolt 3 of today

Apple MacBook 13-inch Touch Pad
Bill Roberson/Digital Trends
Bill Roberson/Digital Trends

Championed by Apple, Intel’s Thunderbolt technology has been around since 2009. However, by the time Thunderbolt 3 showed up in 2016, times had changed. USB-C had emerged as the newest USB connector, complemented by an updated and powerful USB cable that could provide up to 15 watts of power for devices (far more than older standards) and up to 100 watts for charging compatible laptops or similar devices. It was a huge change for USB, and clearly the future of many standard computer connections.

In response, Thunderbolt’s architects made a brilliant decision: Rather than face off against USB-C, they joined it. Thunderbolt 3 ditched the old Mini DisplayPort connector and switched to a USB-C connector, combining the two technologies into one particularly robust hybrid.

The move to USB-C allowed Thunderbolt 3 to make the leap from Apple devices to other PCs and laptops, a process that is ongoing but finally possible. The only downside was the issue of compatibility — Thunderbolt 3’s new USB-C connection isn’t compatible with devices based on Thunderbolt or Thunderbolt 2 without a pricey adapter.

Here are some things you can do with a Thunderbolt 3 port today:

  • Transmit data at a rate of up to 40Gbps, depending on the configuration.
  • Output video to two 4K monitors at 60Hz.
  • Charge smartphones and most laptops with up to 100 watts of power.
  • Connect to an external GPU, depending on the configuration.

If you’re wondering whether or not your USB-C port supports Thunderbolt 3, look for the little lightning bolt symbol next to the opening, which often differentiates it from a standard USB-C port.

The history of Thunderbolt technology


Thunderbolt technology originally began in the late 2000s as an Intel project called Light Peak, which was intended to add optical data transfer to traditional data transfer used with computer peripherals (principally, combining wire and fiber optics). Engineers soon found that their prototypes with standard copper wiring were already achieving the results Intel wanted, but at a much lower cost.

This new product was then released as Thunderbolt in the early 2010s, and at first available only on Apple devices, designed to be a particularly powerful and flexible connection. Compared to the (often brand-specific) cables floating around back then, this was an impressive creation suitable for many purposes. It was particularly promising for designers or engineers who were using laptops but still needed high-powered connections to external storage, high-resolution displays, and similar accessories.

Since the first Thunderbolt release made it out the door with some help from Apple, it was only available for Macs for the first year or so. In addition to limited availability, this new tech required unique Thunderbolt cables, and they tended to be expensive — around $50 or so.

Dan Baker/Digital Trends

Technology marched on. Time had provided a more accurate look at how Thunderbolt was being used and where it should head in the future.

The arrival of Thunderbolt 2 in June 2013 brought several significant changes to Thunderbolt technology. For one, it enabled simultaneous file data and video data transfers — what Intel called “a lot of eye-popping video and data capability.” This was accomplished by combining the two 10Gbps bi-directional channels of the first-generation cable to create a single 20Gbps bi-directional channel. While the overall bandwidth didn’t change, these second-generation cables quickly showed better performance than any other popular peripheral cable of the day.

Another significant change was compatibility with the latest DisplayPort standards and 4K. While still a little ahead of its time, 4K resolution was on the horizon, and users who depended on Thunderbolt connections were glad to know that the highest resolutions would be supported when necessary.

Also, crucially for users, Thunderbolt 2 devices worked with the original Thunderbolt-compatible devices, even if you wanted to mix and match different generations. Again, Thunderbolt would remain an Apple exclusive using the Mini DisplayPort connector until the following generation.

The Thunderbolt 3 standard was announced in June of 2015 and immediately declared “a match made in heaven.” Devices supporting Thunderbolt 3 through the USB-C connector followed in December.

The latest Thunderbolt developments

Dell Thunderbolt Dock TB16
Bill Roberson/Digital Trends

Updates to Thunderbolt continue, as do the growing ways that Thunderbolt is being used in devices. Charging devices using USB-C connections has become more common, and compatibility has pressed onward to include the latest USB 3.2 cable standard, though this is still a work in progress, so always double-check your cables.

New challenges are also growing for Thunderbolt, as impressive as the connection remains. For example, the USB4 standard is on its way, and it finally promises speeds that can match Thunderbolt 3. According to official data, USB4 will be based on Thunderbolt technology to deliver transfer speeds up to 40Gbps when using certified cables — the latest standard, USB 3.2 Gen2, can only deliver 10Gbps. While Thunderbolt is more than just high-speed data, this will put more pressure on Thunderbolt standard engineers to remain ahead of the latest USB specifications.

There are also security threats to consider. Security experts recently warned of the Thunderclap vulnerability on Macs and PCs, which derive from giving recent Direct Memory Access (DMA) privileges to Thunderbolt, USB-C, and FireWire. Malicious peripherals — even add-in PCI Express cards infected in the supply chain — can bypass the security layer managing memory access, allowing hackers to run malicious code on the PC and steal data.

Thunderbolt is of great concern because it’s available on most laptops and desktops sold by Apple. It’s an important reminder that these high-speed connections come with their own risks and should never be used with unfamiliar devices.

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