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We have already shown a number of ways to install and test Windows 8.1 and the latest Windows 10 on your PC, including how to install Windows 10 from USB drive, how to clean install Windows 10 from ISO, create UEFI bootable USB of Windows 10, etc.

Sep 8, 2017 - This tutorial will show you how to install Windows 10 to an external hard drive from an ISO or CD/DVD drive by using WinToUSB.

As many of readers asking to write the best possible to install Windows 8.1 or Windows 10 from an external hard drive, we have come up with this simple guide to show how to install Windows 10 or 8.1 from external hard drive.

We recommend a backup of critical data on the external hard drive as the method requires you format the external drive.

NOTE: In this guide, we have used a PC running Windows 7 to prepare the bootable external hard drive. The procedure is pretty much same on Windows 10 and 8.1.

Make external hard drive bootable to install Windows 10/8.1

Procedure:

Step 1: Connect your external USB hard drive that you want to use as installation media to the PC and backup the data to a safe location as the drive will be erased in the later steps.

Step 2: Open Computer, right-click on the external hard drive icon, and then select Format option to open Format dialog box. Select File System as NTFS, select Quick Format option and click Start button to do a quick format of the drive.

Click Yes for the confirmation prompt. Once the format is done, you will see “Format Complete” message. Click Ok button.

Step 3: We assume that you have a Windows 10/8.1 ISO file. You need to extract the ISO file contents to the root of your external drive. To do this, you need 7-Zip (free), WinZip, or WinRAR software.

If you have any of the above mentioned zip utility on your PC, right-click on the Windows 10/8.1 ISO file and select Extract files option to extract the ISO file contents to the external hard drive.

NOTE: If you are using 7-Zip software to extract the ISO file, right-click on the ISO > 7-Zip > Extract Files option. Make sure that you are extracting the files to the root the external hard drive.

And if you have Windows 8.1 or 10 DVD, simply copy all files and folders of the DVD to the root of the external hard drive.

Step 4: Now open Command Prompt with admin privileges. To open the Command Prompt with administrator rights you can follow any of these steps:

A. Type CMD in Start menu search box and hit Ctrl + Shift + Enter keys simultaneously.

OR

B. Go to Start > All Programs > Accessories. Right-click on Command Prompt entry and select Run as administrator option.

Step 5: In the Command Prompt, type-in the following commands and hit Enter key after typing each command.

x:

cd/boot

bootsect x:

(where “x” is your external hard drive’s drive letter)

(this is the message that you get once the process is completed)

Step 6: Exit the Command Prompt, reboot your PC and then follow the on-screen instructions to install your Windows 10 or Windows 8.1 from the external hard drive.

If you have bought something like a baseline MacBook pro and saved a little cash, but then soon hit with the storage issue when trying to install windows using Bootcamp
We all know that 128 gb is not enought these so we might have bought something like a an external HDD for some additional storage.
In this tutorial is going to tell u how to install windows on to the external drive and save precious 32gb(minimum for windows 10) from your hard drive
This tutorial is based on
Mass storage device won't eject. But I will tell how to add another mac (HFS+) partition that can be used to install mac os apps if you don't need them
Requirments
Mac install windows on external drive
Mac(obviously)
Method 1: Update the Driver Automatically. If you don’t have the time, patience or computer skills to update the Realtek PCIe GbE Family Controller driver manually, you can do it automatically with Driver Easy.
Realtek pcie gbe driver update
 AA=Realtek PCIe GBE Family Controller LAN Driver 585 for WinXP and Server 2003 (5.71 MB) i am trying to install AA= in Windows XP 64bit which is installed in the Dell inspiron 3847 with 3i intel cpu. Network Interface Controllers > 2.5G Gigabit Ethernet > PCI Express. Realtek PCIe FE / GBE / 2.5G / Gaming Ethernet Family Controller Software Files. Under this category, right-click on the Realtek PCIe GBE Family Controller. Then click Update Driver Software 4). Click Browse my Computer for driver software. Click on Browse to find the location of the downloaded driver file. Then Windows will automaticdally find the.inf file in the driver package to install the drivers.
External HDD or SSD(if you are rich?)
External
windows pc(better to have a real windows pc, if not the link above describes how to use a virtual machine)
windows 10 iso(get it from Microsofts website or refer the link above)
WinToUSB
And little patience and persistence to try again if something goes wrong
Make sure to backup anything on your external drive, I can assure u one thing it won't be easy to get it back to get it back once this done, I would also recommend to backup you do a full-time machine backup if you have