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.
The Windows specifications are given below.
- 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
.
- Format the 10 GB partition FAT32 with the label "WINSTALL".
Mount the Windows iso file and copy the contents to the "WINSTALL" volume.
Note: This command will take a while to complete. Be patient!
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.
Next, you need to boot from the volume where the Windows installation files reside.
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.

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.
diskpart
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:
.
remove
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
.
exit
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
.
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.
Write the boot files to the EFI partition. The command to use is given below.
bcdboot w:\windows /s s:
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
Enter the command shown below to quit the Command Prompt Window.
exit
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.

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

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.
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.

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

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.
diskpart
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
extend
The next pair of commands quits dispart
and closes the window.
exit
exit
In the image shown below, select "Continue" to boot back to Windows 10.

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.