I've hit information overload in terms of trying to figure out how to get windows 10 up an running on an external drive. I recently purchased an external 500 GB Thunderbolt 3 NVMe SSD drive with the intention of using it as a boot drive. I made the mistake of not educating myself enough first and now trying to salvage the situation.

I did a lot of reading and now I feel like I am running in circles in terms of possibilities and some article appear to contradict other articles. The biggest problem I find is the articles I am reading tend to be for externally mounted USB drives, or installing windows 10 on macs.

I really liked this article and the first paragraph describing why you might want to do this describes my situation bang on.

I have a Dell Precision 5520 from work that I don't want to mess with the O/S. I do have admin rights on it, but policy will prevent certain software from executing/installing. Its also the only computer I have that has a Thunderbolt 3 port.

I also have Windows 10 installed on two separate USB 3.0 sticks using WINtoUSB. This works great when its up and running but the write speeds to the sticks are so slow that the last windows update took 2 days to complete.

What I have tried so far

My original thought was to use WINtoUSB to install Windows 10 on the external Thunderbolt 3 SSD (ETB3SSD) but its not a USB drive so it does not show up in the list of applicable devices to install to.

My second thought was to use Windows To Go since the laptop its connected to is running Windows 10 Enterprise. However Windows Enterprise ISO is only available through the Licensing Portal. So stop pursuit on this one and did more reading.

Another idea I had was to clone the USB stick to the ETB3SSD, and then repartition the drive to its full size. However I only tried doing this so far while booted off WINtoUSB thumbstick and as a result, not only is the internal SSD not acesible but neither is the ETB3SSD when I plug it in.

Next steps as I see them:

Try cloning WINtoUSB stick to ETB3SSD while running the original windows 10 enterprise on the laptop

Try using Windows To Go to install Windows 10 Pro on the ETB3SSD

Try installing Windows 10 professional on the ETB3SSD and see if it will register with the laptop since the laptop is already authenticated with windows 10 enterprise.

As a last resort when all other options have been exhausted I could install windows 10 professional and purchase an activation key for it. I am only a little scary as I read that windows OS does not like to install on external drives.


What is the best approach for installing Windows 10 on the ETB3SSD?

This is one of the other articles I read on here that relates to mac.

If someone knows better tags for this question, please let me know or edit the question to add them.

UPDATE: 18/11/03 09:10 EDT

I tried cloning the USB stick to the ETB3SDD and it is either not supported or I cloned it wrong. Either way, it did not work.

I also tried Windows To Go but it is looking for a USB drive and the ETB3SSD is not showing up as its not a USB device.

UPDATE: 18/11/05 08:25 EDT

I also have Windows 10 Pro available from another machine if it makes any difference. I do not care if it is windows 10 Enterprise or Professional that winds up being installed on the ETB3SSD.

  • Rufus has an option to copy the iso as a Windows To Go installation. I installed Windows 10 Pro on to an external USB 3 SSD (Samsung T5) using Rufus and it runs very quickly (about 300 MB/s reads and writes), but not sure if it will work with thunderbolt drives. Might be worth trying. – Steve Nov 3 '18 at 16:03
  • I saw RUFUS in my many readings. Part of the information overload I thought it had to deal with MACs for some reason. I will take a look into it. Thanks for the idea. – Forward Ed Nov 3 '18 at 19:46
  • If I understand right, your problem is that you have installed a licensed Windows Enterprise version but lack the ISO. If you have a serial number you could just use the Download Windows 10 page. But if not, then there are other sources (example), and this is perfectly legal since you have a license to use. – harrymc Nov 5 '18 at 10:01
  • Another problem you could encounter is using a non-certified drive, for which there are also well-known solutions, such as in this article. Let me know if my two comments help in solving your problem. – harrymc Nov 5 '18 at 10:05
  • @harrymc As mentioned earlier W10 Enterprise is not available through the first link you provided. There is actually a paragraph on that link stating "Windows 10 Enterprise isn’t available in the media creation tool. For more info, go to the Volume Licensing Service Center.". In light of that it is strongly advised not to download Windows ISO's from non Microsoft sites. I will have to take a run through at the non certified drive option. – Forward Ed Nov 5 '18 at 13:25

Let's see the problems you are encountering.

Problem 1 : Getting Windows 10 Enterprise ISO

For getting a Windows 10 Enterprise ISO from a source that you can trust, how about Microsoft?

To get it from Microsoft itself, see the article
How to Download Windows 10 v.1803 RTM Build 17134.1 Bootable ISO (32-bit & 64-bit).

But as you have now added that you have access to a Windows 10 Pro computer, you may use that computer to download and use the Media Creation Tool.

Problem 2 : Using a non-certified Windows To Go USB Drive

When creating a Windows To Go drive you may get the message:

This is a removable drive and isn't compatible with Windows To Go. Choose a drive that meets the required hardware specifications.

This is because Windows To Go only accepts a limited number of drives that were certified by Microsoft. The following procedure avoids that limitation.

Problem 3 : Creating the Windows To Go USB Drive

This procedure is described in detail in the article Creating a Non-Certified Windows To Go USB Drive, which I will summarize below.

  • Open an elevated Command Prompt (cmd)
  • Enter the Diskpart commands below:

    diskpart                    (enter diskpart)
    list disk                   (locate the USB drive)
    select disk x               (X is number of the drive)
    create partition primary
    format fs=ntfs quick
  • Download the Windows ADK, using in adksetup.exe the Download option rather than Install. You’ll need a Microsoft Account to download the file and to log in to Windows To Go. For getting a Microsoft Account see Create account.

  • Mount the ISO and use 7Zip or a similar tool to open the NEUTRAL.CAB file, extract the file F1_image to an empty folder and rename it to IMAGEX.EXE.

  • Mount your Windows ISO and copy the file \SOURCES\INSTALL.WIM to the same folder

  • Start a Command Prompt, go to that folder and enter the following commands, where X is the drive letter of the USB:

    imagex.exe /apply install.wim 1 X:\
    bcdboot.exe X:\windows /s X: /f ALL
  • If the above commands terminate successfully, the Windows To Go USB is now ready. Be advised that using it is very similar to starting a new Windows installation and there will be many screens and one reboot to go through before it's ready.


An interesting fact was brought to my attention by user @lx07. As described in the TechNet article Windows To Go Step by Step, the Windows ADK is not required, and the imagex.exe call can be replaced by DISM call such as:

dism /apply-image /imagefile:n:\imagefolder\deploymentimages\mywtgimage.WIM /index:1 /applydir:W:\
  • I will give this a go. Now just reading through all this an not actually having tried it, does the fact that the NVMe SSD on the Thunderbolt 3 port not being a USB device make a difference? I am assuming that is what the whole non certified USB stick work around is. The current USB stick I made are not certified and windows to USB worked fine on them with out issue. I really need to try your solution out first – Forward Ed Nov 5 '18 at 21:16
  • What makes the difference is the manufacturer of the USB. – harrymc Nov 5 '18 at 21:20
  • Another comment: I think I made a mistake above and you absolutely need an Enterprise ISO. – harrymc Nov 5 '18 at 21:53
  • Not sure that is a mistake. The WinToUSB key drive can be made from any ISO provided you have a registered copy of the OS. The current USB keys drives I have were made with Windows 10 Pro...unfortunately I can't recall what machine I made it on. – Forward Ed Nov 5 '18 at 21:57
  • You could try - it would be interesting to know if it works. – harrymc Nov 6 '18 at 7:12

These instructions only require the external drive and the Windows 10 iso.

No flash drives, virtual machines, Windows kits (AIK or ADK), or any other third party tools are required.

These are the basic steps needed to install Windows 10 for an EFI boot, when the Boot Camp Assistant will not create the necessary installation partitions and/or the Windows installer will not allow you to select the desired installation partition.

I have made the following assumptions.

  • This drive has a "Device Block Size" of 512 bytes. You can determine the size by examining the output from the command diskutil info disk1. If the size is 4096 bytes, I will have to modify these instructions.

The Windows specifications are given below.

  • Edition: Windows 10 Pro
  • Version: 1709
  • OS Build: 16299.15

Note: To get a better view of the images shown below, either click on an image or open an image in a new window.

  1. Allocate about 10 GB for the installation files, followed by 600 MB of space for the Microsoft Windows Recovery Environment (WRE). The UUID for 10 GB partition should be EBD0A0A2-B9E5-4433-87C0-68B6B72699C7. The UUID for the 600 MB partition should be DE94BBA4-06D1-4D40-A16A-BFD50179D6AC.
  2. Format the 10 GB partition FAT32 with the label "WINSTALL".
  3. Mount the Windows iso file and copy the contents to the "WINSTALL" volume.

    Note: This command will take a while to complete. Be patient!

  4. Create folder named $WinPEDriver$ and copy any Dell provided drivers to this folder. For example, drivers could be downloaded from the Support for Precision 5520 Drivers & downloads website. You should at least add the file 5520-win10-A08-JCMXV.CAB to this folder. This file can be downloaded from the Dell Command | Deploy Precision 5520 Windows 10 Driver Pack website. This file is used in a later step.

  5. Next, you need to boot from the volume where the Windows installation files reside.

  6. Open a Windows Command Prompt window, by following the procedure outlined in this step. Below is an image of what is initially displayed by the Windows 10 installer. Select "Next".


    In the image shown below, select "Repair your computer".


    In the image shown below, select "Troubleshoot".


    In the image shown below, select "Command Prompt".


    The result should be the image shown below.


  7. Use the command diskpart to finish partitioning disk1. The commands you need to enter are given below.

    Note: Sometimes it can take a while for the diskpart command to produce the first prompt. Be patient.

    list  volume

    From the output of the command list volume, determine the number for the volume with the label "WINSTALL". In this example, I will assume this number is 0. Your number could be different. The next command selects this volume.

    select  volume  0

    The commands below change the letter for the "WINSTALL" volume to T:.

    assign  letter=t

    The next command lists all the partitions in disk1.

    list  partition

    From the output of the command list partition, determine the number of the parition with the type "System". In this example, I will assume this number is 1. Your number could be different. Also, determine the number of the parition with the type "Recovery". In this example, I will assume this number is 3. Again, your number could be different. The commands below change the drive letter for the "System" partition to S:.

    select  partition  1
    assign  letter=s

    The next commands effect the "Recovery" partition. The proper attributes are set. Next, the partition is formatted NTFS and given the label "Recovery".

    select  partition  3
    gpt  attributes=0x8000000000000001
    format  fs=ntfs  label="Recovery"  quick

    The command given below creates the tiny 16 MB Microsoft Reserved partition.

    create  partition  msr  size=16

    Finally, the commands below create the partition for the Windows operating system. This partition is allocated all remaining contiguous free space. The partition is formatted NTFS, given the label "DellExt" and assigned the drive letter W:.

    create  partition  primary 
    format  fs=ntfs  label="DellExt"  quick
    assign  letter=w

    The command below quits the command diskpart.

  8. Copy the Windows files to the Windows partition. First, enter the commands given below to determine name of the file containing the Windows files. I will assume the displayed file name is install.esd.

    cd  /d  T:\
    dir  /s  /b  install.wim  install.esd

    If you get the file install.wim, make the appropriate substitution when entering the commands given below. Next, enter the following command to determine the index of the Windows image you wish to install.

    dism  /Get-ImageInfo  /ImageFile:T:\sources\install.esd

    For my install.esd file, the index shown for the name Windows 10 Pro was 8. I will use this value in the command shown below. This command will copy the Windows files to the "DellExt" volume.

    dism  /Apply-Image  /ImageFile:T:\sources\install.esd  /index:8  /ApplyDir:W:\  /CheckIntegrity

    Note: When entering the above command, the parameter /name:"Windows 10 Pro" could have been substituted for /index:8.

  9. Add the Dell supplied drivers need to boot Windows to the drivers store. This can be accomplished by entering the command shown below. I assume you can skip this step.

    Note: You may not need any extra drivers to boot Windows. If the version of Windows is fairly new with respect to the computer, then one would expect all the drivers required to boot Windows would already be included in the Windows ISO.

    dism  /Image:W:\  /Add-Driver  /Driver:T:\$WinPEDriver$  /Recurse  /ForceUnsigned

    Note: If any drivers are ineligible, you may see error messages. This is normal, so such error messages can be ignored.

  10. Write the boot files to the EFI partition. The command to use is given below.

    bcdboot  w:\windows  /s  s:
  11. Disable the ability to boot from the "WINSTALL" volume. This can be accomplished by entering the command shown below. This will rename the folder containing the boot files.

    rename  t:\efi  noefi
  12. Enter the command shown below to quit the Command Prompt Window.


    This should result in an image similar to what is displayed below. Select "Turn off your PC", then wait for the Dell to completely shut down.


  13. You need to finish the initialization of Windows 10. Boot from the partition where the Windows files were installed.

  14. Proceed until you reach the screen where you are prompted for your region. For the 1709 version (OS build 16299.15) of Windows 10, your the screen will appear as shown below. z34

    For other versions of Windows 10, the screen could appear different. As an example, the screen, for the 1507 version (OS build 10240) of Windows 10, would appear as shown below.

    Note: At this point, prohibiting your Dell access to the internet is generally a good idea. For example, unplug any ethernet cables or disable Wi-Fi access that does not require encryption.

    Next, press the control+shift+F3 keys to restart Windows 10 in Audit mode.

  15. When desktop shown below appears, use the Windows File Explorer to create a folder named cabinet on the Desktop. Next, use the Windows File Explorer to open the 5520-win10-A08-JCMXV.CAB file stored in the $WinPEDriver$ folder. Select all the files, then extract to the cabinet folder. When the extraction is finished, run the Setup.exe application in the cabinet folder. After the installer application completes, allow the computer to restart. z31

  16. Next, boot to the Windows Recovery Environment. Basically, hold down the shift key while selecting to restart Windows.

  17. Navigate to a Windows Command Prompt by following the instructions given below.

    In the image shown below, select "Troubleshoot".


    In the image shown below, select "Advanced options"


    In the image shown below, select "Command Prompt".


    After a short delay, you should get an image similar to what is shown below. Choose the Administrator account to continue.


    Next, you should get an image similar to what is shown below. Select "Continue".


    The result should be the image shown below.


  18. Delete the "WINSTALL" partition and extend the "DellExt" volume to reclaim the free space. The procedure is given below.

    Enter the following pair of commands to start diskpart and list the current volumes.

    list  volume

    From the output of the command list volume, determine the number for the volume with the label "WINSTALL". In this example, I will assume this number is 1. Your number could be different. Also, determine the number for the volume with the label "DellExt". In this example, I will assume this number is 0. Again, your number could be different.

    The next pair of commands selects the "WINSTALL" volume and then deletes the corresponding partition.

    select  volume  1
    delete  partition

    The next pair of commands selects the "DellExt" volume and then extends the corresponding partition to consume the deleted space.

    select  volume  0

    The next pair of commands quits dispart and closes the window.

  19. In the image shown below, select "Continue" to boot back to Windows 10.


  20. You will return to the Administrator's desktop displaying the "System Preparation Tool" window. In this window, select "Shutdown" under the "Shutdown options", as shown below.

    Note: Your screen may also include a window labeled "Boot Camp", which can be ignored.


    Next, select "OK" to shutdown the Dell. At this point, you have completed the installation of Windows 10.

    Note: If you prohibited your Dell access to the internet in an earlier step, you may now want to allow access before turning your Dell back on. In other words, plug in the ethernet cable or turn the Wi-Fi back on.

    Next time you turn on your Dell, Windows will start in the "Out of the Box Experience" mode. This is basically the way a newly purchased PC starts up, when Windows 10 is already installed.

If asked, I can clarify any of the above steps

  • Well layed out instructions – Forward Ed Nov 12 '18 at 6:55
  • Not really. This is basically the answer I posted 11 months ago. I deleted all the Apple/Mac references. The answer has been sitting on my computer screen for 3 days. With less than one hour to go, either I posted or delete the answer. Actually, the answer needs to be improved so you do not have to copy the ISO files to the external drive. On Macs this is a requirement, but you have the advantage running an existing Windows from the internal drive. – David Anderson Nov 12 '18 at 7:12
  • hrrmm is bootcamp a mac thing? – Forward Ed Nov 12 '18 at 8:01

What I wound up doing:

  1. Using media creation tool I turned a 128 GB USB 3.0 stick I had into bootable install USB stick. Admittedly I only needed a fraction of the space, but its all I had.
  2. I opened up the laptop and pulled the internal SSD drive. It is the exact same size when reported by some of the disk commands making it hard to distinguish the internal from external drive, and I did not want to overwrite the work drive.
  3. I plugged in the USB Boot/Install stick and the TB3 SSD and powered up.
  4. I hit F12 during power up and selected the USB as the boot device
  5. I then follow the screen prompts and waited for the information to be copied to the new drive.
  6. During restart (I missed that it was restarting) it wound up picking the USB stick as the boot device, so I had to restart it and pulled the USB stick out in the process. Hitting F12 should have worked too.
  7. Windows installed itself on the new drive, I answered a bunch of on screen questions and rebooted.
  8. Something strange happened on this reboot and the bios did some scans. Afterwards and ever since it has started without incident.
  9. I checked to see if windows was activated and it was.

So in general not the same as a WIN to GO drive that you can plug into any machine and will work while isolating the internal drives. This is however an activate windows OS that is restricted to this machine only. Which in my case is fine for now as it is the only comp I have with a TB3 port. Perhaps as TB3 ports become more common I may wish to revisit the other options.

  • If the Windows installer did not complain when you chose to install to the TB3 drive, then there really was no problem to solve. Can I conclude installing to a TB3 drive is no different than installing to an internal drive? – David Anderson Nov 12 '18 at 23:35
  • It appears so, but I was not anticipating that. Now if I could just get BIOS to remember that the TB3 Drive is an option to check in boot sequence even when its not plugged in, then I would be cooking with gas, but alas that is a completely separate question. – Forward Ed Nov 13 '18 at 2:07

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