US How a Thunderbolt port works
A Thunderbolt port is a connection developed by Intel, first with Apple, that combines PCI Express (PCIe) data, DisplayPort video, USB and power in a single cable. The first version appeared in 2011, and every version since Thunderbolt 3 has used the USB-C connector.
Inside the computer, a Thunderbolt controller takes lanes of PCIe and one or two DisplayPort streams from the processor and packs them into a single high-speed link. A device at the other end, such as a dock or an external drive, unpacks them again. Because PCIe is carried directly, a device on a Thunderbolt port behaves almost as if it were plugged into a slot inside the computer.
Many recent mobile Intel Core and Core Ultra processors build the Thunderbolt controller into the processor itself, which is why the port has become common on compact computers and laptops.
Thunderbolt versions compared
Each generation has roughly doubled the bandwidth, and every version since Thunderbolt 3 accepts devices and cables from the earlier USB-C generations, running at the speed of the slowest part. From Thunderbolt 4 onwards, Intel also sets minimum features that every certified port must support.
| Version | Year | Connector | Bandwidth | PCIe | Displays |
|---|---|---|---|---|---|
| Thunderbolt | 2011 | Mini DisplayPort | 10 Gb/s per channel | PCIe 2.0 x4 | One |
| Thunderbolt 2 | 2013 | Mini DisplayPort | 20 Gb/s | PCIe 2.0 x4 | One 4K |
| Thunderbolt 3 | 2015 | USB-C | 40 Gb/s | Up to 32 Gb/s, often 16 Gb/s | Up to two 4K |
| Thunderbolt 4 | 2020 | USB-C | 40 Gb/s | 32 Gb/s, required | Two 4K or one 8K, required |
| Thunderbolt 5 | 2023 | USB-C | 80 Gb/s, 120 Gb/s boost | 64 Gb/s | Two 6K, required |
Thunderbolt 4 is closely based on USB4, and Thunderbolt 5 on USB4 Version 2.0. The extra value of the Thunderbolt name is the certification: a Thunderbolt 4 port must meet every figure in its row, while a USB4 port only has to meet the base USB4 requirements.
What you can connect to a Thunderbolt port
Because the port carries USB, DisplayPort and PCIe, the list of compatible devices is long. The main groups are below.
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USB-C and USB devices. Any USB-C device works, and USB-A devices work through an adapter or dock, at their own USB speed.
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Monitors. DisplayPort and USB-C monitors connect directly, and HDMI monitors through an adapter or dock.
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Docks and hubs. A dock can add Ethernet, several USB ports, audio and one or two displays through one cable. Thunderbolt 4 and 5 hubs can also add up to three more Thunderbolt ports.
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External storage. NVMe SSD enclosures and RAID arrays use the PCIe tunnel for much higher speed than USB 3.2 storage.
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PCIe expansion. Enclosures for network cards, capture devices and graphics cards bring desktop expansion to a computer with no internal slots.
How to recognize a Thunderbolt port
A Thunderbolt port looks exactly like a USB-C port. Look for the lightning bolt icon printed next to it, often with a number for the generation. If there is no marking, the datasheet or the operating system’s device manager is the only reliable check. Thunderbolt cables carry the same lightning bolt on the plug, and passive cables are short: about 2 m for Thunderbolt 4 at full speed and about 1 m for Thunderbolt 5. Longer runs use active or optical cables.
On older computers, a lightning bolt beside a Mini DisplayPort socket means Thunderbolt 1 or 2. These need an adapter to connect to Thunderbolt 3 or later devices.
The firmware matters too. A Thunderbolt port can be limited or switched off in the BIOS, and some systems ask the user to approve each new Thunderbolt device before its PCIe connection is enabled. On a locked-down industrial image, those settings need to be decided before the system is deployed.
Thunderbolt ports on industrial computers
Thunderbolt appears mainly on compact x86 systems built on recent Intel processors. Several of our industrial NUC PCs and 4×4 and NUC motherboards have Thunderbolt or USB4 ports, which give a small chassis the kind of expansion a larger box PC gets from internal slots. That makes a compact computer practical in places where space is tight, such as a kiosk, a cart or the back of an operator console.
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Where it suits. Test and inspection benches, laboratory instruments and control rooms, where an external dock, display or drive is connected and left in place.
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Where to be careful. A USB-C plug is held only by friction, and Thunderbolt cables at full speed are short. In vehicles, on machinery or where cables run more than a couple of meters, internal cards are usually more reliable.
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The alternative for video. For permanent camera or video inputs, an internal PCIe video capture card or a USB video capture device with a locking cable is usually the more robust choice.
Quick answers on Thunderbolt ports
Thunderbolt ports: common questions
What is Thunderbolt 4?
The 2020 version of Thunderbolt, running at 40 Gb/s over USB-C. It adds minimum requirements over Thunderbolt 3: two 4K displays, 32 Gb/s PCIe, charging on at least one port and protection against direct memory access attacks.
What is Thunderbolt 5?
The current version, at 80 Gb/s in both directions. Bandwidth Boost raises the outbound rate to 120 Gb/s for high-resolution displays, and PCIe doubles to 64 Gb/s.
Is a Thunderbolt port the same as USB-C?
It uses the USB-C connector, but does more. Every Thunderbolt 3, 4 or 5 port accepts USB-C devices, but most USB-C ports do not support Thunderbolt.
Can I connect a Thunderbolt device to a computer without Thunderbolt?
Only partly. Many docks fall back to USB with fewer features. Devices that depend on PCIe, such as fast storage enclosures, usually need a Thunderbolt or compatible USB4 port.
Are Thunderbolt 4 and 5 compatible?
Yes. Thunderbolt 5 ports accept Thunderbolt 4 and 3 devices and cables, which run at the speed of the slower part.
We specify and validate Thunderbolt docks, drives and cables with each system as standard, and recommend an internal card instead wherever vibration or cable length makes an external link a risk.