MP 1,1-5,1 Boot into UEFI windows without a EFI card.

[shuotong]

Hi all,
One of my computer recently dies due to broken motherboard, I was managed to plug the Windows 10 boot drive to my Mac pro 4,1 -> 5,1 and booted into the Windows 10 which is configured as UEFI boot.
This can only be done by removing my macOS boot drive from the computer, otherwise I'll boot into macOS. I tried the Boot Drive setting but that creates a legacy environment which only shows me "No boot drive found", which makes sense as legacy boot does not recognize GUID partition at all.
I wonder if the boot selector (hold Command key during startup) will work? I do not have a mac graphics card so I get no boot screen, I randomly guessed a few combinations: press left arrow key once, twice, and tried the right arrow key as well, but I get no luck to boot into either system.
If I leave both drive on the machine, it will boot into macOS, if I choose something in the boot selector, it will not boot into any OS, so I believe the boot selector does work, I may have just missed the correct options. Can someone provide a screenshot of their boot selector page? I have a Macbook pro with retina display and it only shows "Macintosh HD" and "Bootcamp", but I believe Mac pro may have different options like "Optical Drive" "firewire 800"?

 

[Daveiggy]

Try Quickboot, https://www.macupdate.com/app/mac/25414/quickboot

 

[h9826790]

You may install rEFInd, and use hotkey in blind.

 

[startergo]

Once you disable SIP you can actually bless that volume with script or simple terminal commands as well. There was a thread about this. Look in the wiki upgrade section:
https://forums.macrumors.com/thread...-into-my-windows-volume.2144009/post-26594752

 

[shuotong]

Thanks everyone, I got inspired from the quick boot but the developer since to abandoned it for a while. I found something similar that works with UEFI called Boot Manager https://forums.macrumors.com/thread...native-in-the-status-bar-of-your-mac.2145374/
Which is an app with GUI to do the boot drive trick. It does require SIP to be turned off, but I can live with that for a while until my windows computer is fixed.