1. Press the Windows button and type CMD
2. Right-click on Command Prompt and at the bottom of the screen select Run as Administrator . If you don’t do this, you will get an Access Denied error when trying to run Diskpart.
3. You will receive a question from the Windows UAC if you want to allow Command Prompt to run. Press Yes
4. Type Diskpart and press ENTER
5. Type list disk and press ENTER . This will list all the disks that is plugged in to your system.
6. Now you have to select the disk that you want to use as a bootable USB. It’s VERY IMPORTANT that you select the USB that you want to use and not for example the system disk. In my case, I want to select Disk 1, but definately not Disk 0 as it’s my system disk!
When you are sure what drive is your USB, type select disk <number> and press ENTER
7. The next step is to remove the partitions on the drive. As I mentioned before, make sure you have selected the correct disk!
Type clean and press ENTER
8. Now you need to create the primary partition by typing create partition primary and press ENTER
9. Select the partition you just created by typing select partition 1 and press ENTER
10. Type format fs=ntfs quick and press ENTER, to format the drive using NTFS and do a quick format.
10. Make the partition active. If you don’t do this, the USB won’t boot.
Type active and press ENTER,
11. Type assign and press ENTER, to assign the drive the first available drive letter. The drive should now be available in Windows Explorer.
12. Now go to your Windows 8 media, select all files and copy them over to your USB drive.
13. Plug in your new bootable Windows 8 USB to the system you want to install it on. Don’t forget to change the startup order in BIOS, so the USB drive is first in the order.
Now you’re done and you should be able to install Windows 8 from a USB!
Here are all the commands that you needed to type in earlier:
