Follow these steps:
- Insert your USB Flash Drive into an available port.
- Open the Command Prompt (Admin) by right-clicking on the Start button, clicking Command Prompt (Admin), and then click Yes on the UAC prompt.
- Type “diskpart”and press Enter.
- Type “list disk” to determine the disk number of your USB Flash Drive. Type “select disk X”, where “X” is the disk number of your USB Flash Drive.
- Type “clean” to erase the contents of your USB Flash Drive.
- Type “create partition primary size =5000”. This will create a 5GB primary partition on the USB Flash Drive. You can later create an additional partition on the USB Flash Drive for persistent storage.
- Type “select partition 1”.
- Type “active” to make the partition active
- Type “format fs=ntfs quick” to format the partition.
- Type “assign” to give the USB Flash Drive a drive letter.
- Copy the contents of the Windows 8.1 DVD to the USB Flash Drive.
Alternatively, you can download the Universal USB Installer from http://www.pendrivelinux.com and follow the instructions on the site.