iMac Thunderbolt 2 port to Thunderbolt 3 External Hard drive

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iMac Thunderbolt 2 port to Thunderbolt 3 External Hard drive

I have an iMac (Retina 5K, 27-inch, Late 2015) with Thunderbolt 2 ports and have recently purchased a LaCie 2TB Rugged Pro Thunderbolt 3 Portable External SSD.

I have tried to connect them via the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter, but this won't work as it doesn't supply bus power and the LaCie does not have external power.

There is also a StarTech Thunderbolt 3 to Thunderbolt 2 / 1 Adapter, but this is not bi-directional and so won't work in the Thunderbolt 2 to Thunderbolt 3 direction.

Anyone have any other ideas?

Thanks.

iMac 27″, macOS 11.2

Posted on Mar 25, 2021 9:49 PM

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Answer 1

Jack-19

Level 8

46,188 points

Mar 26, 2021 12:22 AM in response to ozbusa

Use USB on the iMac, Thunderbolt on the MacBook.

Use the: https://www.bestbuy.com/site/belkin-3-usb-3-1-type-a-to-usb-type-c-cable-works-with-chromebook-black/9511001.p?skuId=9511001 for the iMac only.

Cheers,

Jack

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Answer 2

rkaufmann87

Level 10

148,458 points

Mar 25, 2021 10:02 PM in response to ozbusa

Replace the drive with one the has it's own power supply.

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Answer 3

Jack-19

Level 8

46,188 points

Mar 26, 2021 7:11 PM in response to ozbusa

Try this;

Reset NVRAM: Reset NVRAM or PRAM on your Mac - Apple Support
Reset SMC: How to reset the SMC of your Mac - Apple Support

Cheers,

Jack

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Answer 4

Jack-19

Level 8

46,188 points

Mar 26, 2021 11:51 PM in response to ozbusa

That's really odd.

Try contacting LaCie support: https://www.lacie.com/support/. (Be prepared to be on hold for a while.)

Cheers,

Jack

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Answer 5

ozbusa Author

Level 1

15 points

Mar 26, 2021 12:51 AM in response to Jack-19

I’ve tried a generic 3.0 USB A to USB C cable but the iMac says the drive requires more power than the USB bus can presently supply. I’ve tried disconnecting all the other USB devices, but it doesn’t help.

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Answer 6

ozbusa Author

Level 1

15 points

Mar 26, 2021 6:18 PM in response to ozbusa

OK, I bought that cable locally and tried it. Still getting the same message:

I've disconnected all other usb devices but the keyboard, and even tried it through a powered usb hub, and still get the same message.

I still have 2 other Thunderbolt external HD's powered through the Thunderbolt ports so don't know if their power draw is added to the usb power draw, but can't disconnect them at the moment to see. Will try that next.

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Answer 7

ozbusa Author

Level 1

15 points

Mar 26, 2021 9:50 PM in response to Jack-19

I tried that a few days ago, but did it again and still no joy.

I unplugged everything else including the 2 thunderbolt HD's but still get the same message.

The LaCie drive does show up in the system report but not in the finder or disk utility.

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Answer 8

ozbusa Author

Level 1

15 points

Mar 26, 2021 12:16 AM in response to rkaufmann87

I also use the drive on a newer MacBook Pro with Thunderbolt 3 where it works fine.

I am trying to find a way to access the files on it on both computers.

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Answer 9

Jack-19

Level 8

46,188 points

Mar 26, 2021 2:24 AM in response to ozbusa

I've had experience with that exact LaCie SSD and that exact cable I linked. It works. Give it a shot if you want, keeping in mind if it doesn't work, there's a return policy.

Cheers,

Jack

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Answer 10

ozbusa Author

Level 1

15 points

Mar 26, 2021 2:34 AM in response to Jack-19

OK thanks I’ll order one and see.

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Answer 11

Jack-19

Level 8

46,188 points

Mar 25, 2021 9:55 PM in response to ozbusa

Hi ozbusa,

You cannot get near the speeds with that drive with that Mac, nor use Thunderbolt.

My Suggestion:

Return the SSD
Get a cheaper SSD, such as: https://eshop.macsales.com/item/OWC/ENVPK01/?fullDetails. This can get 1000 MB/s.
Connect with USB, since Thunderbolt in this case is impossible, and USB with the SSD listed above will give you 400-450 MB/s.

Again, no SSD with your Mac will get over 450 MB/s, so you are wasting your money with the LaCie.

Cheers,

Jack

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iMac Thunderbolt 2 port to Thunderbolt 3 External Hard drive

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