Mac Pro 5,1 may require Mac-EFI graphics-card to Install firmware upgrade for High Sierra as reported by chelidon here:
Re: How do I find the Mac Pro 5,1 Mid 2010 firmware latest update
Dunno if this helps, but i’ ve been having a bear of a time trying to get it installed on my Mac Pro5.1.
I have a Mac compatible- EFI video card( sapphire Radeon 7950), 26 gigs ram, 2 hard drives in there, and the latest firmware and boot rom versions.OS is 10.12.6 on the main drive and 10.12 on the other one, it’s a 12 core Mac from 2010-2011, haven’t got it to install yet-not for lack of trying though
Still waiting for a bug fix from you-know- who, maybe an explanation.
John B
Mac compatible- EFI video card( sapphire Radeon 7950),
...that card is notorious for having the wrong markings on its on-board switch (EFI, non-EFI). in recent macOS, it is likely to run in either mode.
It may be worth a shot to try the switch in the opposite of its current position (be sure to note the position that is working for you before you start).
Oh my gosh.... holy cow..it’s incredible..it works!! I tip my hat to you Mr. Grant Bennett-Alder. You were absolutely correct, that was what the problem was.I didn’t think that my Mac Pro would boot up with the switch in#1 position, so I left it at#2 position. This has been driving me nuts for 5 days, and now it’s solved. I can’t thank you enough so I’ll just say ‘ many thanks to you’ and wish you a great day
John B
I'm not sure if my experience is evidence, but I didn't have any luck installing the HS firmware update on my 4,1 flashed to 5,1 with a non-EFI card installed. I put in the original GT120 and the upgrade went on without a problem. After HS was installed, I put the other graphics card back in (MSI 7870), and everything works fine.
This has now been confirmed by at least one other User.
Any reports of bad outcomes thus far?
So what version of firmware is showing now?
menu > About this Mac > system report
...older MP51.007F.B03, or a newer version?
It's a newer version
MP 51.0084.B00
JB
again thanks
setting up that new iCloud is a pain in the butt though.....
oh well, at least it's working now
Thanks. This worked for me. I switched to another position and used HDMI instead of miniDP port to install firmware and start the high Sierra install.
Mac Pro 5,1 may require Mac-EFI graphics-card to Install firmware upgrade for High Sierra
