So I'm having trouble installing any kind of OS X on my 2006 Mac Pro 1,1. Sierra won't work. El Capitan won't work. Yosemite seems like it's really, really hard to get working and I haven't tried any other version before that.

I'm looking for a guide to follow, where I can install either Yosemite, El Capitan, or Sierra on it. I have a Macbook Pro where I've aquired the original installers ready to put on the machine.

My real questions are: Where can I find that guide? If this is impossible, what is the highest version I can install? Mavericks? Mountain Lion?

  • Offically, by Apple standards, this model is maxed out at Lion (10.7.x). Anything newer might work but will involve some heavy hacking and installing an unsupported operating system. Another workaround is to use bootcamp and setup a Windows installation. Even though it officially supports only Windows 7, I bet Windows 10 would work. I'll probably try installing an unsupported macOS just because it's cool :)
    – www139
    Aug 10, 2018 at 19:43

5 Answers 5


It sounds like you have a mac pro 1,1 like mine with Quad core 2.66GHz processors.

It is correct about the 32 bit EFI on these systems but there is a workaround with a re-written bootloader for the MacPro 1,1 that will enable you to run El Capitan (last OS before Sierra) flawlessly on your Mac Pro. It even includes a script that will check and fix the bootloader each restart which means you can install system updates without having to repatch your system each time.

You will need a better video card. I suggest one with at least 1 GB of video RAM. There are a lot of PCIe graphics cards out there that will work in a MAC but they don't boot EFI which essentially means you will get a black screen during boot up until the boot has completed - then the video card will switch on. This is only an issue is you have to boot into a separate hard drive or a Bootcamp partition. You won't be able to see your selections once booting and holding down the OPTION key right after the chime. You will have to find a fully Mac Compatible video card if you want boot screen graphics.

To get El Capitan to install on a MacPro 1,1 you need several things:

  • an 8GB USB
  • a copy of the Mac App Store El Capitan installer
  • at least 12GB of RAM
  • a video card capable of running the latest OpenGL and with at least 512MB of video memory - 1 GB is better.
  • You will need to rebuild the installer to work with a MacPro 1,1 and to use the 32bit EFI translator. Instructions and the links for the downloads can be found here.

No Mac OS after Lion will install on a MAC PRO 1,1 without editing the original install file. Apple places checks in the installer so that it will only work with certain motherboards. Part of the tweak to the installer involves adding your system's board ID to the installer so it will pass a check and install. There are tools and instructions for how to rebuild the installer for Mountain Lion (uses MlPostFactor which is a "patched" install and not native - certain kernel level functions will fail such as "Bootcamp" also Little Snitch and Hands Off will not work) Mavericks, Yosemite and El Capitan.

El Capitan is about the easiest OS to modify because Captain Pike's Script automates the entire process. No real advanced knowledge or manual editing of system files is required. I followed the instructions, downloaded the script, let it do its thing and I have a flawless MacPro 1,1 running OS X El Capitan.

I also recommend adding an Airport Extreme wireless card and a Bluetooth card for your machine. I don't think you will find a Bluetooth card for the MacPro 1,1 that will work with OS X's "Handoff" feature but if you are using an iPhone you will want it to be able to sync with your Mac Pro without having to plug it in, so you will need the AirPort and the Bluetooth to get the most out of your Mac. They are easy to find, relatively easy to install and are fairly cheap. Instructions for how to perform these upgrades can be found here.

Incidentally El Capitan is the last OS so far that you can tweak to run on an old MacPro 1,1. If you are having trouble finding a Mac App Store copy of El Capitan, Google is your friend for finding torrents. Just make sure to include the words "pirate" and "MAS El Capitan torrent" in your search terms.

  • why the downvotes on this answer? A lot of good info here Jun 6, 2017 at 19:47

The highest version is El Capitan OSX 10.11.
It will not run macOS Sierra 10.12 due to CPU.
We have two MacPro1,1s running El Capitan.
Our steps are:

  1. Use an officially supported Mac to install the OS on the hard disk.
  2. Replace boot.efi in two places, add entry to PlatformSupport.plist.
  3. Move the hard disk to the MacPro1,1 and boot.

Each step can be involving, and we have taken a few iterations to get it right. It can be done. The result is good.


There was an app called MLPostFactor for installing Mountain Lion on unsupported Macs (specifically the Mac Pro 1,1), while I don't know how to use it myself there is a guide here [link] (https://forums.macrumors.com/threads/guide-success-install-10-8-on-old-unsupported-mac.1325709/) and you can probably find more info online by searching.

Whether you choose to use this app or go with the newest officially supported version (10.7.5) you will need an HDD on which to put an initial installation of Snow Leopard (10.6.3, followed by an upgrade to 10.6.8) as you will need the AppStore to get ahold of the digital only installers for any newer version of OS X/macOS.

You can find a Snow Leopard install DVD here: (it was the last version of OS X to be sold on physical media, and is thusly still available on Apple's website brand-new for people who want 10.7+ and need the AppStore to get it) [link] (http://www.apple.com/shop/product/MC573Z/A/mac-os-x-106-snow-leopard)

Finally you could potentially install OS X Mavericks via a distro like Niresh, or install macOS El Capitan/Sierra by hacking up a custom installer for yourself, but I would discourage either as both would involve going full Hackintosh, and aside from being technically illegal Hackintosh Distros like Niresh are often very buggy, always poorly supported, oftimes difficult to get ahold of and commonly branded to high hell by whoever stitched it together, and always full of enough bloatware to rival a Samsung flagship phone. As far as making your own installer goes it is less a matter of it being pheasable or legal and more a matter of how much time you are willing to put into it, as you would likely have to replace the kernel (and possibly have to write the replacement yourself), all essential drivers including graphics, manually extract and copy the installer image verbatim to an external media after said modificafions followed by setting up a MacEFI compatible bootloader like CloverEFI or Chameleon/Enoch and making sure it would be able to boot 64-bit (unless you also modified the installer to perpetually launch everything in 32-bit mode, which is possible but a hassle). So at the end of the day unless you are truly dedicated it would probably be your best bet to simply use the AppStore to upgrade to 10.7.5, or buy/build a newer Mac if you need it to run anything 10.9+

  • Thanks for the reply! I'm currently trying to install Lion 10.7 (although I was getting some installation error :-() and then I will try to upgrade to El Capitan from that. As long as I know people can install El Capitan on Mac Pro 1,1, I'm going to attempt that. Feb 20, 2017 at 21:31
  • @MortenMoulder well +1 for dedication I suppose, can't fault you for that. I know it took me a while (~8 months) to finally get El Capitan installed on my custom Mac build (it's a hybrid of an iMac, Mac Pro and Mac Mini), and it is certainly worth it in the end. Many improvements have been made to macOS over the years and the newer versions are a pleasure to use. Plus once you're already on El Capitan you will likely have an easier time upgrading to newer versions of macOS (I recommend MultiBeast's system definition feature to ease installation.). Good luck! Feb 20, 2017 at 21:37
  • Great advice! Yeah, I don't see much point running an old OS (I don't consider El Capitan old yet) on a dual quad core Xeon build haha. Thanks! Feb 20, 2017 at 22:07
  • If it's a dual quad, it's not a 1,1 It might be a 2,1 or later. Serial number will remove all doubt, as per Steve's comment on the other answer.
    – Tetsujin
    Feb 21, 2017 at 8:34
  • @Tetsujin Upgrading this sucker to dual quads :) Feb 21, 2017 at 22:18

I do not think you can officially install Mavericks. I believe Mavericks will requires a 64 bit EFI. Your Mac has 64 bit processors, but the EFI is 32 bit. You probably can run 64 bit Windows and many 64 bit versions of Linux, but not 64 bit only versions of OS X or any version of macOS.

If interested in attempting a install Windows 10 or a current version of Linux, let me know.

BTW, you can install Windows 10 before having to buy a license. If you decided to keep Windows 10, you would need the license to activate.


A Mac Pro 1,1 could be any of those. All of them can run 10.7.5 (Lion), at least if equipped with enough RAM:

This system can run the last version of OS X 10.7 "Lion" if upgraded to at least 2 GB of RAM. However, although it has a 64-bit processor, it has a 32-bit EFI and cannot boot in 64-bit mode. It also does not support "OpenCL" running the default video card or the other build-to-order video cards that were offered via custom configuration. Please also note that OS X Lion is not capable of running Mac OS X apps originally written for the PowerPC processor as it does not support the "Rosetta" environment.

You might be able to run Mountain Lion, although unsupported.

  • I have some weird suspicion this isn't a Mac Pro 1,1. When I pull out the RAM ricers, I can see it has 12GB RAM installed. It looks like factory 800 MHz RAM. Which Mac Pro configuration comes with 12GB RAM installed? I haven't been able to fire it up, because it came with no HDD, so I'm kind of stuck here. Feb 20, 2017 at 19:22
  • 1
    Easy enough to find out. the serial number is on the bottom ledge of the PCI slots. support.apple.com/en-us/HT201764 Feb 20, 2017 at 19:49

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