How to install windows 8.1 with EFI boot to external hdd on iMac late 2013

blackwhite999 said:

hi everyone,
How to install windows 8.1 with EFI boot to external hdd on iMac late 2013?
I'm playing Fifa 15 on bootcamp. pls help

Click to expand...

Just run Boot Camp assistant and that's it.

Haswell Macs will install Windows in UEFI via Boot Camp Assistant automatically.

Edit: Saw that it was for external drive.

I used this guide: http://www.admin-magazine.com/Articles/Putting-Windows-8-on-a-USB-Drive

But somehow, it won't install in EFI. I formatted my external drive with GUID partition table and FAT32, then used gdisk (command line utility) to remove hybrid MBR so that it would appear as GUID to both OS X and Windows, and still it doesn't install in EFI.

I've used this a few times with success

http://bleeptobleep.blogspot.co.uk/2013/02/mac-install-windows-7-or-8-on-external.html?m=1

I'm glad I came across this post. I just bought an external thunderbolt ssd and want to install windows 8.1 on it for gaming. I currently have an iMac 2013 and windows 7 on it partitioned using boot camp. My goal is to delete windows 7 and use the 1tb fusion fully on OS X and install windows 8.1 on the external ssd. Do I have to remove windows 7 first or can bootcamp recognize two windows? I would like to get 8.1 going first before I remove windows 7 if that's possible.

blackwhite999 said:

hi everyone,
How to install windows 8.1 with EFI boot to external hdd on iMac late 2013?
I'm playing Fifa 15 on bootcamp. pls help

Click to expand...

Update:

I got EFI booting to work on an external Windows to Go drive. You'll need a Windows virtual machine in Parallels/VMware.

Here are the instructions:
Connect external drive to Windows VM.

What you need:
install.wim file (obtain this from your Windows ISO)

Open elevated cmd.exe

Note: All commands aren't case sensitive, including pathway to files.

Type diskpart
Type list disk
Take note of the disk you want to select
Type select disk 1 (if your disk is Disk 1)
Type clean
Type convert gpt
Type create partition EFI size=100
Type format quick fs=fat32 label=EFI
Type assign letter=S
Type create partition primary
Type format fs=ntfs quick label=W2G (or any other name you wish for label)
Type assign letter=E
Type exit

Open up File Explorer. In your C drive, create a new folder named WIN2GO.
Put the install.wim file in this folder

Back in cmd.exe:
Type dism /apply-image /imagefile:C:\WIN2GO\install.wim /index:1 /applydir:E:\ (this process will take quite a while)
Type E:\Windows\System32\bcdboot E:\Windows /s S: /f UEFI

Restart your entire Mac. After the chime, hold down Option and when prompted to select your boot drive, select EFI Boot.

Proceed installation normally.

After installation, install Boot Camp drivers.