Frequently Asked Questions about Thunderbolt 3

Thunderbolt 3 adopted the USB-C connector mainly because it is compact. Although both technologies use the same connector, the compatibility between them is limited.

Please find below answers to common questions regarding the Thunderbolt 3 interface.

How can I tell if my computer has a Thunderbolt 3 port?
Consult your computer documentation for Thunderbolt 3 compatibility.  A Thunderbolt 3 port on a computer is a USB-C port with the Thunderbolt icon, a lightning bolt next to it. See the image below:

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How can I identify a Thunderbolt 3 cable?
A Thunderbolt 3 (USB-C) cable is reversible and identical on both ends. It has the Thunderbolt icon and the number 3 on the connector. See the image below:

Connector face Cable end
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Are Thunderbolt 3 and USB 3.1 (USB-C) storage devices interchangeable?

  • A Thunderbolt 3 computer port can support both Thunderbolt 3 and USB-C devices.
  • A USB 3.1 (USB-C) computer port can only support USB devices.

Are USB 3.1 (USB-C) cables and Thunderbolt 3 cables interchangeable?

  • Thunderbolt 3 cables support Thunderbolt 3 and USB 3.1 (USB-C) devices.
  • USB 3.1 (USB-C) cables do not work with Thunderbolt 3 devices.
  • A Thunderbolt 3 storage device requires a Thunderbolt 3 cable  and a Thunderbolt 3 port on the computer.

What is the performance difference between USB 3.1 and Thunderbolt 3?

Protocol Theoretical burst transfer rate
Gigabits per second (Gb/s)
USB 3.1 Gen 1 Up to 5 Gb/s User-added image
Powered USB 3.1 Gen 1 Up to 5 Gb/s User-added image
USB 3.1 Gen 2 Up to 10 Gb/s User-added image
Powered USB 3.1 Gen 2 Up to 10 Gb/s User-added image
Thunderbolt 3 Up to 40 Gb/s User-added image

Is a Thunderbolt 3 storage device backwards compatible with Thunderbolt and Thunderbolt 2 computers?
Thunderbolt 3 technology is backwards compatible with Thunderbolt 1 and 2, however adapters are required since Thunderbolt 3 uses a different interface than the previous generations. Additionally, some features unique to Thunderbolt 3 devices, such as charging capability, may not work when using adapters. Another important factor is that not all adapters are bi-directional, which means connecting adapters to Thunderbolt 3 devices may not function with Thunderbolt 2 or Thunderbolt 1 computers or vice-versa.

Some of our Thunderbolt storage devices have multiple interfaces (e.g. Thunderbolt 3 and USB 3.1) so they can be used on systems that do not support Thunderbolt 3.

We strongly recommend to always connect using Thunderbolt 3 when available to take full advantage of Thunderbolt 3 performance.

The device with Thunderbolt 3 must provide its own power. Since the LaCie Rugged SSD Pro does not provide its own power this device will not work with Thunderbolt 3 to Thunderbolt 2 adapters.

Note: We cannot guarantee that all adapters will be fully functional with Thunderbolt 3 devices.

Are all Thunderbolt 3 (USB-C) cables created equal?
No, in fact, there are two types of Thunderbolt 3 (USB-C) cables, passive and active. Passive cables cost less and can reach up to 40 Gb/s data transfer if the length is 0.5m or less and 20 Gb/s if over 0.5m. Active cables can reach up to 40 Gb/s data transfer with a length of up to 2m.