A: Most USB boot sticks are formatted as NTFS, which includes those created by the Microsoft Store Windows USB/DVD download tool. UEFI systems (such as Windows 8) can't boot from an NTFS device, only FAT32.

Therefore you need to create a bootable USB device that's formatted as FAT32 instead, then copy the contents of the Windows installation media to it. For example use the commands below to create a FAT32-formatted USB device:

  1. Open an elevated command prompt, then start the diskpart utility:
    diskpart.exe
  2. List all the disks and identify your USB stick:
    list disk
  3. Select the disk number that is your USB stick, e.g.,:
    select disk 4
  4. Remove all existing partitions:
    clean
  5. Create a new partition, make it active and format as FAT32, then assign a drive letter:
    create partition primary
        select partition 1
        active
        format quick fs=fat32
        assign
  6. Exit diskpart:
    exit

diskpartfat32sml
Example of Diskpart Output in Response to Commands Above

The final step is to copy all the files from the Windows install media to the USB device--for example, where d: is my ISO mount of Windows media and f: is my USB stick:
 

xcopy d:\* f:\ /s /e

You can now boot your UEFI system and install Windows from this FAT32 USB drive. (See my FAQ about installing UEFI to a Windows machine.)