I purchased the OWC Accelsior S PCIe to 2.5 SSD Host adapter to install Windows on my 2009 Mac Pro. However, Boot Camp sees the SSD as an external device and doesn't allow it.

I've read that some users have used the Apricorn Velocity Solo with some success but others have reported the same problem with this card as well. I have this card on order and will be testing it too. More on this to come.

I can install an OS (in my case, FreeNAS, based on FreeBSD) on a SSD while connected to built in SATA channel, then move it to a PCIe adapter, but it won't boot. It only boots if connected to one of the 6 built-in SATA channels.

Is is possible to get an SSD to show up as an internal device with ANY PCIe card? If so, do you know of a list of cards that do work?

  • Just as a test, would BC allow you to install to any regular non-system drive on the SATA? If it would you could try a 2 step, install there then move it with Paragon etc
    – Tetsujin
    Commented May 25, 2017 at 9:36

1 Answer 1


Apparently it is not possible to have neither a PCIe flash nor PCIe-attached SSD drive show up as internal on a Mac Pro. I tried multiple PCIe flash and PCIe SATA cards and none showed as internal, even those claiming to be bootable on Mac.

On a side note, even though I could not get FreeNAS (FreeBSD based NAS software) to boot from a PCIe add-on card, I was able to install Windows 8.1 on a PCIe flash drive and it shows up in the boot menu when holding down the Option key as EFI.

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