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Guide: Multibooting UEFI on Separate Drives

Probably because it isn't bootable. macOS installation media for UEFI booting is GPT with 2 partitions, the installer base system is on an HFS+ partition and Clover (that makes it bootable) is installed to a separate FAT/ESP/EFI partition. The path the firmware looks in for the executable is //EFI SYSTEM PARTITION//efi/boot/bootx64.efi. If you are already using the Unibeast/Clover installer is it possible you installed to the wrong EFI partition?
It's strange that it's not bootable, because I've already used this usb drive to install osx on my notebook about 3 years ago. I'll try to create the bootable usb again. Hope it will work

Thanks you
 
@Going Bald I have been working with @pbryanw on getting some of my issues worked out with my Sierra install and I have now moved on to loading Win10 on a seperate SSD. @pbryanw gave me some additional steps to follow along w/ your initial instrustion in this post, but I am running into the following issues.

Getting the following Error: Windows could note prepare the computer to boot....


See my screenshot of my partitions and error. (BTW, I disabled my macOS SSD per @pbryanw recommendation. The only thing you see is the new SSD and another HDD for storage). Should I diabled the other HHD drive as well for purposes of installation?
IMG_0534.JPG
IMG_0532.JPG
IMG_0533.JPG
 
@brennan.ruth0723

Best to have only the target drive connected when installing Win10.
Follow this to set up a clean drive for Windows installation:
- boot Windows installer USB
- at first screen press Shift+F10 to get command prompt
- type: diskpart
- type: list disk (so you're certain on the disk you're working with - best to be only disk connected - say it is disk 0)
- type: select disk 0
- type: clean (this does exactly that - it wipes the disk clean)
- type: convert gpt
- type: create partition efi size=200
- type: format quick fs=fat32 label="EFI"
- type: exit
- type: exit

Now select the free space showing in the partition selection window and click Next button; installer will take it from there, creating partitions as needed.
 
I used the WMC tool, but if you want to restrict the installer to UEFI or Legacy BIOS only installation then the Rufus tool allows you to do that. Either one works. If using diskpart to clean/convert to GPT/create & format EFI partition FAT32 fails to work (I cannot see why it would do so), then try formatting the drive for a Mac OS install.
Boot the Windows media, select the Mac partition, delete it, click next.
 
Hi! I'm trying to install Windows 10 on a separate HHD. I have OSX Sierra installed on a SSD and using Clover to boot.
I've made an USB with a Windows 10 installer on my MacBook, as shown in this guide.
When I'm going to the boot menu I get both the normal USB and the UEFI USB, but neither work. When choosing the UEFI the screen gets black and I get back to the boot menu. When using the other (not the UEFI) I just get the message that I have to use a boot device and then press a key.

I got the Gigabyte GA-Z270X-Ultra Gaming mother board. Is there anything I have to change in the bios to get to the windows installer? As said before, I'm currently running OSX Sierra without problems.

I've been trying for many days now, and this is so frustrating!

Thanks.

It's fixed! Thanks to the community.
 
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I think that you installed windows in UEFI mode, isn't it?
 
I think that you installed windows in UEFI mode, isn't it?

No, but i figured it out. After several days..!
The problem was the usb installer. It was made using the terminal on another Mac. Tried many times without luck. But when using Boot Camp Assistent to create a bootable usb with Windows, it worked.
 
I don't have any problem with clover booting windows in UEFI mode. I have windows and osx on separates hds and i didn't have any problem.
Always do the same procedure. Install windows in UEFI mode, and then install OSX. There is no problem. Clover boot windows always. Install windows with usb prepared with rufus.
 
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