I have the Mac Pro "Quad Core" 2.66 (Original):

  • Model identifier: 1,1
  • Ram: 32 GB
  • Graphics Card: GeForce 7300 GT
  • Hard Drive: 750GB HDD Seagate

I have the Mac Pro currently running Mac OS X Lion and would like to update this to Mac OS X Yosemite or Mac OS X El Capitan if possible. I was wondering what kind of upgrades I would need to do to make this possible and the best way to do it for as low cost as possible.


Since this thread came up near the top of a google search, and since I've done it before, I thought I would chime in just in case someone else looking for info sees it.

My Pro 1,1 with 32GB RAM, an SSD, and an ATI 5770 runs El Cap absolutely great. The only big issue is that it uses quite a lot of power compared to a modern machine. No, it's not as fast as a new mac, but it's totally capable of being a daily driver for most uses.

You can NOT brick your machine doing this. All you are doing is booting from a slightly modified El Cap install. There is no need to upgrade your EFI to the 2,1 roms unless you will be upgrading your CPUs. There is no need to flash your video card's ROM to a mac version. You will need a more recent video card--I use a 5770.

The process is simple. Install El Cap on an SSD/HD using another mac that does support El Cap, disable csr, and then change the boot.efi file to an alternate ( https://github.com/Piker-Alpha/macosxbootloader ) optionally using a script to make things easier ( https://github.com/ryanmaclean/Mac-Pro-1-1-El-Capitan-Upgrades ).

If your video card isn't a mac version, your screen will be blank (no boot logo) until your desktop comes up, but that's never been an issue. You may need to fix the boot.efi file after an update, but I don't imagine that happens much any more.

Other than that, enjoy!


Both my ati 5770 and my nvidia 660ti work on my pro 1,1 with ElCap. While it is true that older cards wont let you boot and only suffer a few seconds of blank screen, it is not due to a lack of EFI bios on the cards. There isn't an EFI bios available for any 5770 afaik, and Zotac was not kind enough to provide an EFI update for my particular 660ti. I am sure of this due to working through these issues getting PCI passthrough to work with KVM/qemu with these cards on another box and having to substitute an EFI rom via a file. But, yes, if you have a pc/win card older than 2012 or so, you might need to flash for mac or find a more recent card.

  • Older non-EFI cards or ones without Mac support won't work. Your 5770 is fine, but something like a PC 2600XT wouldn't work, despite the Mac version being fine. – JMY1000 Sep 12 '17 at 1:26

I used to have one of these, unfortunately there is no supported way to install those OSs on this particular system. Though they are 64bit machines the EFI boot loader is 32bit.

There are hacks out there that let you install later OS versions on a MacPro 1,1. I think MacRumors.com has a long thread of people who have done this and likely other places as well. But I am unsure if this is considered off-topic or not for Ask Different, so that is far as I will go.

  • As far as I can tell the question itself isn't off-topic, so feel free to edit your answer if you'd like. Basically, the question is still about installing original Apple software on original Apple hardware and it's specific enough (i.e. the OP has a specific problem that can be answered one way or another), so I see the question as being on-topic.. – Monomeeth Mar 18 '17 at 23:55

What you want to do is not an easy task. I'm not saying it's impossible, but you do risk bricking your machine. I assume you have some software that requires Yosemite or El Capitan, so only you can decide whether the risk is worth it.

The trick is not as much about the hardware as it is about convincing your old Mac Pro to run in 64-bit mode. That's because your Mac can't natively boot OS X Yosemite or El Capitan without a different boot loader.

I have seen a number of approaches used to get these machines to work with newer OS versions, so it's too hard to try and summarise these here. Below are some links for you to check out:


  1. The above solutions are not without risk - including the potential to brick your machine!
  2. If you proceed, ensure you have a full backup of your data.
  3. Personally, I would not bother - your machine originally launched with Mac OS X 10.4.7 and only officially supports up to Mac OS X 10.7.5 - so you can imagine how well the hardware will run Mac OS X 10.10.x or Mac OS X 10.11.x.
  • I understand the skill and patience required to pull this off but what is the ultimate worst case scenario, I loose all my data or I completely brick the computer? – Rs Graphics Mar 19 '17 at 18:50
  • Well, if you don't have a backup, then losing all your data would be a worse case scenario in my opinion. But, yes, it is possible you could also brick the computer. Obviously, all anyone here can do is answer the question you've asked. But behind many questions is a context we can't guess - for example, we have no idea why you want to upgrade to either Yosemite or El Capitan and, depending on your reasons, there may be other solutions. If you don't have another Mac, I would avoid trying to upgrade it - but if not, then only you know whether it's worth the risk. – Monomeeth Mar 19 '17 at 20:58
  • The MacRumors forum discussion I linked to is very long, so before proceeding I'd read it all and make note of anything that is of interest or concerns you. You should also get a sense for the success rate of doing this, and for how well the Mac Pro will run the OS. Then you can decide whether the risk is worth it. – Monomeeth Mar 19 '17 at 20:59

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