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According to this list my tricked out mac pro won't run Sierra. Tricked out with 20gig of memory a big SSD and lots of HDD. Sad.

enter image description here.

Historically how has Apple enforced this? And has there been a way to defeat it? Or is there an actual hardware reason as far as anyone knows?

Thanks!

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    As I don't know specifics... The installer looks for the model number in the system's firmware. However there are hacks that let you install newer MacOS on "unsupported" hardware. A little googling on something like "sierra on unsupported mac" should get you there... Aug 11, 2016 at 23:35
  • In addition to what @SteveChambers said, take a look at the Macrumors forum for Mac Pro, they are very good at describing how to get older Mac Pros running new software.
    – At0mic
    Aug 12, 2016 at 0:44

2 Answers 2

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Though the Mac Pro 4,1 won't run Sierra, the Mac Pro 5,1 will.

Apparently, the Sierra installer only looks for the 5,1 firmware, not the 2009 tag.

The thing about the 4,1 & 5,1 is they are so similar, it's possible to turn one into the other with a simple firmware update.

I have never personally done this, mine was bought already upgraded. The original hack is at http://forum.netkas.org/index.php/topic,852.msg5004.html#msg5004 Which links to a user-made utility to allow this to be changed in both directions, 4,1 to 5,1 & back again. It apparently uses the official Apple Firmware updater as part of the process.
You can pre-empt the download by fetching the 5,1 firmware first, directly from Apple

There are 69 pages of comments... which, honestly, I haven't read. Early theories were that this would allow the machine to use Westmere CPUs - which is now known to be true.

From page 68, this is apparently the process for El Capitan...

  1. Boot into recovery mode and disable SIP since I'm running El Capitan
  2. Reboot
  3. Mount the MacProEFIUpdate dmg (for 5.1)
  4. Run MacEFIRom's utility.
  5. Shutdown and power back up by holding the power button until light flashes and beep sounds
  6. Verify Boot ROM Version: MP51.007F.B03
  7. Boot into recovery mode and enable SIP
  8. Reboot
  9. Reset PRAM

Just to prove it does work, screenshots from my own machine, originally, I think, a Nehalem 4-core, now a Westmere dual 6-core

enter image description here

From Apple KB: About EFI and SMC firmware updates for Intel-based Mac computers

enter image description here And a comfirmation image from the netkas thread...

enter image description here

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I believe your original GT120 video card will also be a problem as that is not supported (need something that will work with the new Metal API). I briefly got my upgrade 4,1 (now 5,1) Mac Pro to work but ran into some boot issues and found it easier to roll back that diagnose them at this time.

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  • Actually I performed the procedure as described above and have had no problems with Booting. That's just one data point of course :)
    – pitosalas
    Dec 13, 2016 at 21:31

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