Apple Thunderbolt Display requires native Thunderbolt, not just USB-C

Apple made its popular Apple Thunderbolt Display from 2011 to 2016–we still get questions about using the display eight years after it was discontinued. Even though the Thunderbolt Display used an older Thunderbolt standard, it remained compatible with Thunderbolt 3 when that newer standard was released, as well as with the even fresher Thunderbolt 4.

The Apple Thunderbolt Display offered a Thunderbolt 2 data connection via a jack that is identical in appearance to Mini DisplayPort. Thunderbolt 3 requires USB-C, a standard that can connect devices and computers using Thunderbolt 3/4, USB 3.1 and later, and USB4. USB-C is a specification for ports, jacks, and cables; Thunderbolt and USB’s numbered standards define what flows over those connections. (There were some tweaky elements of using Mini DisplayPort and Thunderbolt 2 when Apple transitioned from the former to the latter, but none of that is relevant with USB-C or Thunderbolt 3/4.)

If you want to use a Thunderbolt Display, most people rely on Apple’s Thunderbolt 2 to 3 adapter, for which Apple still charges a whopping $49. This adapter has a USB-C jack on one end, and you can only get the display to work if it’s plugged into a Thunderbolt 3 or 4 port on your Mac or an external Thunderbolt dock.

Plug it into a USB 3.x/USB4 port on an external dock or a USB 3.x/USB4-only port on certain Macs (like the lower-end Mac Studio models’ front two ports) and the display doesn’t function.

The reason is convoluted. The display relies on DisplayPort data coming from the computer to show the screen. However, even though USB 3.x/USB4 support passing through DisplayPort data, the hardware on the Apple Thunderbolt Display can’t interpret that—it only has a chip that can accept Thunderbolt-encoded information, including the method by which DisplayPort is wrapped up for Thunderbolt.

It’s one of the remaining cases where USB-C frustrates an average user with a mix of older and newer gear. The telltale is the lightning bolt symbol on Apple’s adapter: there’s a Thunderbolt lightning bolt on both the input side (for Thunderbolt 2) and output (for Thunderbolt 3/4). The USB logo is entirely different and absent.

Learn more about connecting older Apple displays to a Mac.

This Mac 911 article is in response to a question submitted by Macworld reader Mike.

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