Mac Pro 5,1 Startup Manager problem (with or without EFI card)

Ok, so I fixed it. The solution isn't particularly elegant but at least everything works now. And it's easy to switch between the two OSes.

Rebooting from Windows into macOS worked from the get go. The problem was that I couldn't get back to Windows without resetting the NVRAM. That's fine for running Windows but what if you want to switch back to macOS?

Once you reset the NVRAM, the graphics driver switches back to the default option, which doesn't work with Nvidia cards... I had to VNC my way into the machine to select the proper driver and reboot before I could see anything on the screen. That was cumbersome but before I even came up with this I had to switch back and fourth between the GPUs every time I wanted to reboot and change OS (because I have an ATI 5750 and a 1080Ti, I would need 3x 6pin pcie connectors to connect them all at the same time). That was a pain! But now I've found an even better solution.

I had to disable SIP (which may or may not be a great idea but I guess we managed to live without it before the El Capitan days) because with SIP on, you can't use commands to manually change the startup disk... Speaking of commands here is a brief overview of my first ever Applescript which ended up fixing my problem:

do shell script "sudo mkdir /Volumes/EFI" with administrator privileges

do shell script "sudo mount -t msdos /dev/disk0s1 /Volumes/EFI" with administrator privileges

do shell script "bless -mount \"/Volumes/EFI\" -setBoot --nextonly" with administrator privileges

tell application "Finder"

restart

end tell

The first line creates a mount point to access the partition we're trying to boot up from.

The second line mounts it to the desktop. (very briefly, because this whole thing finishes in less than half a second)

The third one sets the newly mounted partition as the startup disk.

The rest of the code is there to reboot the mac.

With this code, you don't even need to worry about the Startup manager! Just switch on the Mac, if it boots into the wrong OS, just reboot to the other using either the bootcamp utility (from Windows) or the script (from macOS!).

TLDR:

If you have the same issue, download this script, open it with the Applescript app, run it once or twice to make sure it fixes your problem. If it does you can then export the script as an app (that's what I did) and just double click it to restart into Windows. But remember you NEED TO DISABLE SIP FIRST!

Final notes:

- I said this wasn't the most elegant solution because whatever you do, you still need to allow the script to make some changes (that's because we're using a sudo command and there's no way around it). That basically means that every time you want to restart into Windows you need to type your admin password. That's the only problem with this script.

- This piece of code is a mash up of codes from here and here. Special thanks to the guys who wrote these otherwise I probably wouldn't have been able to write my script.

But I haven't upgraded to Mojave and I probably won't until the proper macOS drivers are released, which could very well mean I'll never ever upgrade to Mojave on this machine.

10.13 + Win 10 + MacPro5,1 is supposed to work. A lot of people got it to work. I am 110% sure there's an issue with my partitioning.

All of this would be fixed if I could get the "EFI boot" partition to show up inside the Startup Disk control panel. Alternatively, is there a terminal command to set up the next startup disk based on the disk name (i.e. disk1s1 etc...)?