User profile for user: mudbucker
mudbucker Author
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USB4 cable confusion

Ever since I got my first MacBook Air (Intel 2020) with only Tbolt3 ports I’ve been dealing with the typical USB cable mess…dongles, hubs and docks...to connect my older devices with USB-B to A cables. Currently I am using a CalDigit TS4 dock for this. Other than the dock, I do not own any Tbolt devices at this time.


All new devices I've purchased (at this point an HDD, a passive USB hub with an SD reader, SSDs, thumb drives and an audio interface) have USB-C connections but none of these are Tbolt, all are either USB 2.0, USB 3.2 gen 1 (5 Gbs) or USB 3.2 gen 2 (10Gbs). The bus powered SSDs came with really short cables (one foot or less). So I’ve purchased Tbolt 4 cables to use with the ones I need longer cables for. So far I have bought cables from CalDigit and OWC as the Apple cables are way too expensive.


Apple states here that Tbolt cables will not work properly with USB devices and to only use USB cables with them. This has NOT been my experience. As expected, my Tbolt 4 cables work fine with all my USB-C devices regardless of speed and About This Mac confirms it.


Today I saw an Amazon Basics 1 meter USB4 cable that claims to be compatible with Tbolt 3 and 4. It only caught my eye because they are a few bucks cheaper than OWC (which are a few bucks cheaper than Cal Digit). However, no sense wasting my money if there might be compatibility issues down the road if/when I add any Tbolt peripherals.

MacBook Air 13″, macOS 12.7

Posted on May 8, 2024 4:16 AM

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User profile for user: Servant of Cats
Servant of Cats
User level: Level 8
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Posted on May 8, 2024 1:51 PM

mudbucker wrote:

Apple states here that Tbolt cables will not work properly with USB devices and to only use USB cables with them. This has NOT been my experience. As expected, my Tbolt 4 cables work fine with all my USB-C devices regardless of speed and About This Mac confirms it.


I believe you're looking at a case of bad technical writing.


USB-C is a connector and a set of standards for allowing multiple protocols to run over it. Thunderbolt is one of those protocols – an optional one. Most USB-C host ports on Macs happen to be Thunderbolt ports, and Apple tends to refer to those ports as "Thunderbolt" ports.


There are some Mac USB-C host ports that are not Thunderbolt ports:

  • The USB-C ports on 12" Retina MacBooks (Early 2015 – 2017)
  • The front-panel USB-C ports on M1 Max Mac Studios
  • The front-panel USB-C ports on M2 Max Mac Studios

You cannot plug Thunderbolt devices into those ports and expect them to work. I think that's what Apple is trying to say (poorly) in the Support article.


As far as I know, you can plug in a Thunderbolt cable (rated to carry data at up to 40 Gbps) and use it to carry data for other USB-C protocols at lesser speeds. It won't turn the connection into a Thunderbolt one; it will just provide a high-quality connection for the protocols that are in use.

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User profile for user: Servant of Cats
Servant of Cats
User level: Level 8
37,001 points

May 8, 2024 1:51 PM in response to mudbucker

mudbucker wrote:

Apple states here that Tbolt cables will not work properly with USB devices and to only use USB cables with them. This has NOT been my experience. As expected, my Tbolt 4 cables work fine with all my USB-C devices regardless of speed and About This Mac confirms it.


I believe you're looking at a case of bad technical writing.


USB-C is a connector and a set of standards for allowing multiple protocols to run over it. Thunderbolt is one of those protocols – an optional one. Most USB-C host ports on Macs happen to be Thunderbolt ports, and Apple tends to refer to those ports as "Thunderbolt" ports.


There are some Mac USB-C host ports that are not Thunderbolt ports:

  • The USB-C ports on 12" Retina MacBooks (Early 2015 – 2017)
  • The front-panel USB-C ports on M1 Max Mac Studios
  • The front-panel USB-C ports on M2 Max Mac Studios

You cannot plug Thunderbolt devices into those ports and expect them to work. I think that's what Apple is trying to say (poorly) in the Support article.


As far as I know, you can plug in a Thunderbolt cable (rated to carry data at up to 40 Gbps) and use it to carry data for other USB-C protocols at lesser speeds. It won't turn the connection into a Thunderbolt one; it will just provide a high-quality connection for the protocols that are in use.

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User profile for user: Servant of Cats
Servant of Cats
User level: Level 8
37,001 points

May 8, 2024 1:53 PM in response to mudbucker

mudbucker wrote:

Today I saw an Amazon Basics 1 meter USB4 cable that claims to be compatible with Tbolt 3 and 4. It only caught my eye because they are a few bucks cheaper than OWC (which are a few bucks cheaper than Cal Digit). However, no sense wasting my money if there might be compatibility issues down the road if/when I add any Tbolt peripherals.


Note that USB4 defines both a new USB4 20 Gbps transfer mode and a new USB4 40 Gbps transfer mode. If you are considering buying a cable because it is rated for "USB4", you might want to know which speed it supports …

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USB4 cable confusion

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