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User profile for user: Stephen Blaze
Stephen Blaze Author
User level: Level 1
8 points

2021 iMac Thunderbolt ports - not compatible with *some* external drive enclosures?

Discovered a quirk with the two Thunderbolt 3 / USB 4 ports on my new M1 iMac – there is an apparent incompatibility with a type of external drive enclosure that I own (when others work fine).


After waiting way too long for a Time Machine backup drive to be recognized by Migration Assistant (initially plugged into one of the Thunderbolt ports), it otherwise worked instantly when plugged into one of the non-Thunderbolt ports. So, after the migration completed and I was up and running (and an extra restart too for good measure), I did some investigation and process-of-elimination, results below. Note that my iMac has four ports – two "Thunderbolt 3 / USB 4" ports, and two "USB-C 3.1" ports.


  • Tested two USB 3.0 flash drives – they both work on all four ports.
  • Tested both HDD and SSD drives on a Unitek SATA-to-USB 3.0 adapter – they work on all four ports.
  • Neither HDD nor SSD in either of my two Aukey 2.5" SATA-to-USB 3.0 drive enclosures work on the Thunderbolt ports (nothing even shows up in Disk Utility).
  • Yet, both HDD and SSD work fine in the Aukey enclosures when plugged into the non-Thunderbolt ports.
  • I replicated all the above using different cables too, to rule out that variable.


Thus, for this iMac at least, this type of Aukey drive enclosure + Thunderbolt port = ☹️


Interestingly, these Aukey enclosures continue to work fine, as they have for years, in all four Thunderbolt ports on my 2017 MBP… 🤔


Now that I've narrowed this down and know not to use those specific enclosures on those specific ports on my iMac, this isn't something that I particularly need to resolve; however, it is worth getting this information out there – this incompatibility quirk could be very frustrating, especially for those versions of this iMac sold with only two ports (both Thunderbolt).

iMac 24″, macOS 11.4

Posted on Jun 15, 2021 1:12 PM

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User profile for user: HWTech
HWTech
User level: Level 9
55,958 points

Posted on Jun 17, 2021 5:54 PM

I cannot easily find the USB chipset used in any of the Aukey products as the manufacturer doesn't list them anywhere that is easy to find (perhaps they just change the chipsets on every production run to whatever they can get the cheapest at the time).


You may never get a definitive answer on the underlying issue here except to know that the Aukey enclosure won't work on your iMac's USB4 port (whether this happens on other M1 Macs with USB4 ports is hard to say without other users confirming). I had a similar issue with some early USB3 drive docks & hubs on my 2014 Mac Mini which required me to use a powered USB3 hub in order to use my USB3 devices (I still don't know if this was limited to just my Mini or if it also occurs on other ones). While the USB3 drive enclosure should work on the USB4 ports I find that manufacturers don't always implement or follow the standards like they should. These are not the first times I've been shown positive proof of a third party peripheral/accessory causing problems on a Mac, yet works perfectly fine on non-Macs or perhaps even older Macs. I'm finding the quality of products from all manufacturers is getting worse and worse even from manufacturers that typically produce high quality products.

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User profile for user: HWTech
HWTech
User level: Level 9
55,958 points

Jun 17, 2021 5:54 PM in response to Stephen Blaze

I cannot easily find the USB chipset used in any of the Aukey products as the manufacturer doesn't list them anywhere that is easy to find (perhaps they just change the chipsets on every production run to whatever they can get the cheapest at the time).


You may never get a definitive answer on the underlying issue here except to know that the Aukey enclosure won't work on your iMac's USB4 port (whether this happens on other M1 Macs with USB4 ports is hard to say without other users confirming). I had a similar issue with some early USB3 drive docks & hubs on my 2014 Mac Mini which required me to use a powered USB3 hub in order to use my USB3 devices (I still don't know if this was limited to just my Mini or if it also occurs on other ones). While the USB3 drive enclosure should work on the USB4 ports I find that manufacturers don't always implement or follow the standards like they should. These are not the first times I've been shown positive proof of a third party peripheral/accessory causing problems on a Mac, yet works perfectly fine on non-Macs or perhaps even older Macs. I'm finding the quality of products from all manufacturers is getting worse and worse even from manufacturers that typically produce high quality products.

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User profile for user: Stephen Blaze
Stephen Blaze Author
User level: Level 1
8 points

Jun 17, 2021 8:26 AM in response to HWTech

Alas, no chipset information provided under SysInfo – just a Product ID (0x1066) and a Vendor ID (0x2537).


I did find a closed forum thread with similar issue, about the same Aukey enclosures my T-bolt ports ignore : New M1 Mac Mini unable to see SSD in USB-… - Apple Community


I replicated their workaround by putting a (old, unpowered, no-name USB 2) hub between my iMac and the enclosure, and voilà, the enclosure actually works that way on the T-bolt ports. So it's definitely a chipset thing. The other thread's user didn't specifically state if their enclosure worked on the mini's USB type A ports, but it infers that it did, which would seem to track with how my enclosures work with the non-T-bolt ports, no hub needed.


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User profile for user: Stephen Blaze
Stephen Blaze Author
User level: Level 1
8 points

Jun 15, 2021 5:44 PM in response to tbirdvet

Your suggestion intrigued me as the curl of the cables naturally favor one orientation… I tried flipped from usual, in all four ports, alas, with same results – the Thunderbolt ports ignore the Aukey enclosures, while the non-Thunderbolt ports see them just fine. Since every other gadget I've tried works as expected in the Thunderbolt ports, I'm not too worried about this, and I've put stickies on the enclosures to remind me. I may have never even noticed this quirk had I not happened to plug the enclosure into a Thunderbolt port rather than a "regular" port.

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User profile for user: HWTech
HWTech
User level: Level 9
55,958 points

Jun 16, 2021 10:33 AM in response to Stephen Blaze

What is the controller is used on the Aukey? Check the System Profiler to see if it provides this information. You will need to click on either USB or Thunderbolt depending on the protocol used by your external drive. I know that some USB chipsets are known to be incompatible with an M1 Mac. I know when the M1's were first released the JMicron chipset was one as several users posted that on these forums as well one of the device manufacturer's mentioning the JMicron chipset issue on their product website (now removed). I know that at least one user implicated a specific chipset from another USB chipset manufacturer, but I don't recall which one. I tend to purchase products with the ASMedia USB chipset and they seem to work on my M1 Mac (although I haven't used them a lot yet).


Unfortunately I've never seen any articles with any specific details on this compatibility issue and there have only been a few posts on these forums from users who had technical knowledge to provide this information (along with a few vendors which mentioned the issue).

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2021 iMac Thunderbolt ports - not compatible with *some* external drive enclosures?

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