I installed a 480GB Kingston Predator PCIe flash SSD in a 2009 Mac Pro. It worked great after installing macOS Sierra. Boots fast and is very snappy.

Went to install Windows using Boot Camp and I couldn't get past the error:

You cannot partition an external disk, a RAID disk or an internal disk on which FileVault encryption is in progress. Restart your computer using an internal disk that is not part of a RAID set or try it again after FileVault has completed.

For some reason either Mac Pro or macOS Sierra sees the PCIe SSD as an external drive.

Is there any way to make it appear as an internal drive or any way I can dual boot into Windows if I cannot get past this error in Boot Camp?

  • 2
    PCIe disks always appear as external. My OS is on a OWC SSD connected via PCIe on my Mac Pro. I do not know of a way to spoof it as an internal disk (let me know if you find a way, I've been looking for one too), but I do know that any of the SATA cables will read disks as internal so if you get an M.2 to SATA adapter and put the SSD in a drive bay or in with the DVD writer area (there is a free SATA cable there unless you've used it), you will be able to do what you want with it (including boot camp).
    – NoahL
    Jan 16, 2017 at 1:48
  • 1
    There's maybe this alternative, to install it on an external drive - apple.stackexchange.com/questions/218105/…
    – Tetsujin
    Jan 16, 2017 at 6:46

1 Answer 1


I was able to add a second PCIe flash card and install Windows directly without the use of Boot Camp Assistant. I was also able to do the same by using Apple Disk Utility to create a free partition on the macOS drive for Windows and install it that way as well. However I opted for the second PCIe flash card to keep things simple and segregated.

Now, when I boot and hold the Control key, I get "Macintosh HD" and "EFI Boot", the later of which is Windows.

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