Installing and running windows from a USB3 SSD on an iMac

Looks like a great performer! I probably won't be using this as I already have a spare LaCie Rugged TB lying around that I'm planning to put Samsung EVO 850 in. Did you have to plug in the power brick or was it working purely with bus power?

 

Got a very nice SSD with Thunderbolt from Monoprice.com and installed a Boot Camp'd Windows 8.1 on it. (I need it sometimes for my work in certain USB-intensive situations in which running Windows in a virtual machine, as I do daily, won't do.)

Great price, and it works well.

 

Will definitely be trying this sometime soon

 

I used another method of my own, which installs Windows in an UEFI environment on both USB or Thunderbolt.

Here's my steps:
Connect external drive to Windows VM. You must have a Windows VM in VMware/Parallels.

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.

 

A few weeks ago I've gotten the Transcend JetDrive 725 1TB for my rMBP '12 and has been putting off setting up the included enclosure with a fresh install of Windows 8.1 on the Apple's 512GB PCIE SSD. Until today, I was stubborn and tried using both Winclone and Win2Go to clone the Bootcamp partition from my iMac 5K which won't boot properly due to driver problems. Now, I've used Win2Go to fresh install Windows 8.1. Booting up was faster than I've remembered Bootcamping rMBP '12 must be faster processors.

What can I say, the setup works great so far with speeds exceeding 2.5" SSDs. Games load like a dream! Now booting Windows for gaming won't feel like a chore anymore. Tomorrow I'll figure out if BootChamp would work with this setup. This must be one of the most economical external PCIE SSD solutions available!

 

Uh, it isn't PCIe. It's only mSATA.

PCIe SSDs in Apple Macs are only available in late-2013 and later rMBPs.

PCIe speeds are around 700 MB/s, far higher than the maximum 625 MB/s theoretically supported over USB 3.

 

My bad. Yep, Apple's SSD from 2013 onwards are really fast indeed.

 

masotime

I am trying the same thing with a 64gb USB 3.0 sandisk usb drive but mine never gets past the windows 8.1 screen with the spinning circle. I use dmy spare windows machine to dump the iso with wintousb. DId you do anything else? I am on a 2014 macbook air

 

Okay went through your instructions with zero issues after the dummydisk driver but after reboot the drive doesn't appear in the boot menu. Here is what my 2 partitions look like.

 

I'm running windows on an external USB3 drive too, and I have used almost the same method that yjchua95 described. I followed these instructions, it worked perfectly:
http://bleeptobleep.blogspot.be/2013/02/mac-install-windows-7-or-8-on-external.html

The drive need to be directly attached to the machine, when it was connected to my USB3 hub, it didn't boot...

 

drive or flash drive? I got it to see my drives now under refit but they failed to load, so now I am very puzzled

 

A 500GB Seagate drive
I've failed twice: one time because the drive was attached to the USB3hub, and one time because I've tried with Windows 7. With Windows 8.1, it works perfectly.

And another piece of advice: when you prepare your key with a Windows installation or a virtual machine, it must be a 64bits version of Windows running, or your installation will fail...