New NVMe drive is slow on thunderbolt 3

I decided to test my new NVMe drive speed and was astonished how slow it was 42mb/s. I tried a different cable same result. So then I tested the same drive with a thunderbolt 3 to USB adapter and it was 400+ mb/s. This is a 2019 iMac with i9. Anyone know what might be going on?

Posted on Jul 21, 2019 11:46 AM

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2 replies

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Jul 22, 2019 12:32 PM in response to david from milwaukie

Hello,

Please reach out to the drive’s manufacture for further assistance.

Jul 22, 2019 12:53 PM in response to david from milwaukie

Are you sure the drive is Thunderbolt 3 (lightning bolt icon on the connector), not just USB-C. If you use a Thunderbolt 3 cable with a non-Thunderbolt USB-C device, it may run at USB 2.0 speeds, which would explain your 42MB/s.

If the connector has no lightning bolt icon, use a USB-C 10Gb/s cable, not Thunderbolt 3. For short cables (0.5 m) they are the same, but not for longer cables.

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New NVMe drive is slow on thunderbolt 3