iMac Pro and Thunderbolt 3 Transfer Speed Limitations?

[kcrossley]

I purchased an OWC Express 1M2 external enclosure and paired it with a 4TB Samsung 990PRO M.2 SSD to use with my iMac Pro. When I ran the Blackmagic Speed Test, I only got around 960MB/s. The 990PRO is capable of 7450MB/s. I reached out to OWC technical support, and they said their enclosure is limited to 990MB/s because of some kind of restriction Apple imposes on external Thunderbolt 3 drives. They even have it documented on their website: https://eshop.macsales.com/shop/owc-express-1m2

Has anyone ever heard of this? Is there any way around the 990MB/s limitation?

Thanks!

 

[Bigwaff]

Has anyone ever heard of this? Is there any way around the 990MB/s limitation?

You purchased a USB4 enclosure. Thunderbolt 4 supports USB4. Since iMac Pro has Thunderbolt 3 ports, the USB4 enclosure backwards compatibility is USB3. You need a TB3 enclosure.

OWC Envoy Pro SX Thunderbolt (40Gb/s) Bus-Powered... at MacSales.com

TB3ENVPSX0T OWC Envoy Pro SX Thunderbolt (40Gb/s) Bus-Powered Portable NVMe M.2 SSD Enclosure Kit. High performance enclosure kit for NVMe M.2 2280 SSDs. Designed for Thunderbolt 3/Thunderbolt 4 (USB-C) Macs and PCs.

eshop.macsales.com

 

[kcrossley]

You purchased a USB4 enclosure. Thunderbolt 4 supports USB4. Since iMac Pro has Thunderbolt 3 ports, the USB4 enclosure backwards compatibility is USB3. You need a TB3 enclosure.

OWC Envoy Pro SX Thunderbolt (40Gb/s) Bus-Powered... at MacSales.com

TB3ENVPSX0T OWC Envoy Pro SX Thunderbolt (40Gb/s) Bus-Powered Portable NVMe M.2 SSD Enclosure Kit. High performance enclosure kit for NVMe M.2 2280 SSDs. Designed for Thunderbolt 3/Thunderbolt 4 (USB-C) Macs and PCs.

eshop.macsales.com

That's what I thought as well, but when I asked the OWC Tech Rep if the Envoy Pro SX would work, she said it has the same limitations as the OWC 1M2.

 

[Bigwaff]

That's what I thought as well, but when I asked the OWC Tech Rep if the Envoy Pro SX would work, she said it has the same limitations as the OWC 1M2.

Baloney. However, Envoy Pro SX is TB3 only - no USB fall back - but since you are using it w/ iMac Pro TB3 ports, all good.

 

[kcrossley]

Baloney. However, Envoy Pro SX is TB3 only - no USB fall back - but since you are using it w/ iMac Pro TB3 ports, all good.

Ok, that sounds good. I'm ordering it now. I'll circle back when I have everything set up and report my findings. Thanks for your help.

 

[kcrossley]

Baloney. However, Envoy Pro SX is TB3 only - no USB fall back - but since you are using it w/ iMac Pro TB3 ports, all good.

Dude, you were right! I'm getting over 2,500 MB/s read/write speeds with the Envoy Pro SX. Thanks for your help.