Trying to reinstall El Capitan on a Mac Pro

Good afternoon,

I’m trying to reinstall El Capitan in a Mac Pro Model # A1186 2.66QX. I’m doing this for a friend so I know nothing before receiving it. It currently boots into recovery mode. When I choose to reinstall the OS, it starts the reinstall process after connecting to the App Store. Screen says that it’s “downloading additional resources and will restart automatically.” The process either hangs after a few hours or goes back to the OSX Utilities screen.

I even purchased a El Capitan boot flash drive to see if that would do the trick.

When I try to boot from the flash drive after holding down the option key, the machine shows the flash drive as an option. I click on it and the boot process starts and the slider gets about halfway along, then the screen goes black for a second and then comes back on but then boots into the recovery menu. Can’t get it to boot into the installer.

I’m assuming El Capitan is the right OS for the machine as that’s the recovery it boots into.

Thanks for any help you can give.

Andy Enzminger

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Given the age of that Mac, lighting candles might be the thing…

But, and a long shot, try replacing the CR2032 battery on the motherboard, it seems to preserve settings around startup. Page 50 on the manual (and I note the explosion warning, never noticed that before…)

I would start by moving the installer flash drive to other USB ports and seeing if that did the job.

If it’s a 2x 2.66 GHz Mac Pro, that means it’s a first generation MacPro1,1.

The MacPro1,1 model only supports up to OS X Lion 10.7.5 without modification.

There are hacks that allow unsupported versions of OS X up to El Capitan to be installed on these machines. I don’t have personal experience with this model, but there are a few threads in the MacRumors forums that might be helpful:

Maybe others here can give better advice.

Thank you to both of you. I had seen that also on my searches and it does explain a lot of things. How the El Capitan recovery partition got there will just be a mystery as I don’t know anything about who had the machine before. Lion will be fine for what this machine will be used for.

Thanks again