Installing Windows 7 to 2TB EFI External Hard Drive

Grimat · 13 Mar 2015

First of all I know that installing Windows on an external hard drive is far from ideal, and this is only meant as a temporary solution. My SSD died, ordered a new one, seller sent wrong one and have to go through return procedure. I need access to Windows on my desktop urgently, and the only drive I have at my disposal is a 2TB EHD, and my PC will only boot EFI and ACHI.

The Petition Table of my EHD is as below:

I have a laptop with x64 Windows 7 Home Premium in which I've used the fast installer tool here, and followed the instructions:
How To Install Windows 7 On USB Flash Drive or External Hard Drive

However when I plug it into my desktop, and select the drive from the boot menu it doesn't boot

Ztruker · 13 Mar 2015

~~I had this link squirreled away, maybe it will help: How To Install Windows 7 To USB External Hard Drive [Must Read]~~

Got to learn to read better

whs · 13 Mar 2015

Long time ago I wrote a tutorial on how to do that. Maybe you want to try. But I warn you - it is going to run like molasses from a HDD - and forget USB2. eSata is best. You are better off with a fast USB3 stick with an access time under 1ms. It is the 15ms access time of a HDD that kills you with the OS.

Windows 8 To Go - Setup on a USB Flash Drive or USB Disk

gregrocker · 13 Mar 2015

How was the HD transferred onto the external?

You can try removing the 2.5" laptop HD from the external to install it in the laptop but I would not sacrifice the external because it is going to be a long shot given numerous hurdles I'll explain.

The chief problem that most installs moved to new hardware won't boot due to a conflict between drivers, HID and SID. This is normally resolved using Paragon Adaptive Restore disk to Adjust Win7 to boot on new hardware with Paragon Adaptive Restore CD however the version in the tutorial does not have EFI support, so if it won't start even with Startup Repair you'd need to look into the latest adaptive restore with EFI Support to either transfer the or adjust the image.

If that is your only copy of an important install I don't think I'd mess with it, but instead use a copy. I'd keep it pristine so that when your new SSD arrives you can clone it directly using a flexible app like Macrium Imaging - Windows 7 Help Forums.

As to making the external bootable via USB, it would need to be installed that way and that can't be done with the existing as far as I've seen. But it may depend upon how the image got there and how it is otherwise preserved if at all.