I did repair my early 2009 mac pro 4.1; and after installing a gtx970 I did realize that I may use it also for windows gaming.

Although my main drive is just a boot for OSX, which is a 90 GB SSD drive; the rest of my home directory and application support is on a SATA mechanical drive. Is possible to install Windows 10 via bootcamp, on a drive that is not the main drive? I am running 10.11 (el capitan), which is the highest OS that my machine seems to be able to run.

EDIT No, I am not using an external drive, but an internal drive (the Mac Pro has 4 internal SATA bay for drives)


1 Answer 1


Below is a quote taken from the Boot Camp Installation & Setup Guide (copyright 2013).

• If you have a Mac Pro with more than one internal disk and you want to install Boot Camp on a disk that isn’t in the first hard drive bay, remove the drives in the lower- numbered bays. You can reinstall the drives after you install Boot Camp.

So, it is possible to install Windows via Boot Camp, on a drive that is not the main drive. The maximum Windows that Apple officially supports is Windows 8.1 (64-Bit). Microsoft says you should be able to upgrade an existing Boot Camp Windows 8.1 installation to Windows 10.

Everything I have posted so far is by the book. However, you are proposing going off script by directly installing Windows 10. Officially, the answer is no, but unofficially the answer probably is yes. If you try, expect to encounter Scarecrows. In other words, expect error messages from Apple as some point during the installation that will say you can not proceed. There is usually are one or more ways to bypass any problems that you will encounter. You can try posting a problem here and see if anyone can suggest a solution.

Here is some advice.

  • Burn the Windows 10 ISO to a DVD. You may need a DL DVD.
  • Install a BIOS booting Windows.
  • Before installing, make sure the Widows Support Software has been copied to a FAT formatted flash drive.
  • Select the Master Boot Record partitioning scheme when using the Disk Utility to erasing the flash drive.

BTW, you do not need a license to try Windows 10. You can download and install without a Product Key. If you choose to keep Windows 10, then you will need to purchase a license.

There is always the possibility that Windows 10 is not compatible with your processor. I assume the Windows 10 installer would inform you, if this was the case. I have encountered PCs where I could install 64 bit Windows 7, 8 and 8.1, but not Windows 10. Basically, the processor did not meet the requirements given below. (This was taken from the Microsoft web site: Minimum hardware requirements, Section 3.1 Processor)

  • Compatible with the x86 or x64 instruction set.
  • Supports PAE, NX and SSE2.
  • Supports CMPXCHG16b, LAHF/SAHF, and PrefetchW for 64-bit OS installation

On the other hand, I came across the Microsoft website: Windows Processor Requirements, which states:

Intel Xeon processors are supported on Windows 10 Pro for Workstations and Windows 10 Enterprise only

Apparently, you can download and try Windows 10 Enterprise for free. See the Microsoft Evaluation Center website.

If you do not use the Boot Camp Assistant to install Widows, then you should follow the instructions provided by Microsoft. For BIOS booting Windows, the instructions for partitioning can be found at the BIOS/MBR-based hard drive partitions website.

I would recommend placing the System partition on the first (main) drive and then placing the Windows and Recovery partitions on a second internal drive. You could combine the Windows and Recovery partitions, if you wish. This System partition is only appropriately 100 MB in size, so the partition should have minimum impact on the space for macOS.

Note: The Microsoft instructions do no include the Mac requirement that any drives that share macOS and a BIOS booting Windows must by Hybrid partitioned.

  • Thanks David; sadly my situation is less than ideal, since I am using an old 4.1 mac pro; which has no chance to upgrade to newer builds; and as such I can't directly install W10 as you are aware of. I did encounter errors, issues and tried workaround; and only at that point I gave up and posted here; because I am assuming that there are others with a mac pro 4.1 that are able to run windows on these machines. I will try to break down the problem and post specific questions; since at this point, I have tried enough workarounds to be more specific than few days ago. Thanks
    – rataplan
    Jan 2, 2019 at 1:06
  • 1
    @heyjude: The oldest Mac that I have installed 64 bit Windows 10 on is a 2007 iMac. Your 2009 Mac Pro should prove easier than what I had to do. Try to outline the steps you believe would lead to success and I will try to comment. Jan 2, 2019 at 3:41
  • Thanks for your words of encouragement. So far I tried to run bootcamp assistant from vanilla OS; and tried also to remove the entries in the info.plist so my machine would not be in the black list; but it did prove to be useless, since from my understanding, modifying the plist won't affect the app since 2014. All the videos that I have found on youtube show a 3rd option that use an ISO to create the installer on bootcamp assistant, but I get only 2 options, and I am not able to load my W10 iso anywhere.
    – rataplan
    Jan 2, 2019 at 7:49
  • And using the W10 dvd that I burned, does not go forward either, since I get the message that say that I can only install up to Windows 8. Tried to install windows 7 (which is what was running on that machine few years ago), and even that did not work; since when windows installer did reboot and started to write on the disk, it would give me an error when I selected the disk in bay 1 (the one I did assign as windows entirely in the bootcamp assistant)
    – rataplan
    Jan 2, 2019 at 7:52
  • @heyjude: My answer does state expect error messages from Apple as some point during the installation that will say you can not proceed. Are you now ready to abandon using the Boot Camp Assistant to install Window 10 or do you still need more time? BTW, I updated my answer. Jan 2, 2019 at 16:45

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