How to reboot Your Computer from USB Flash Drive
Sometimes, you will find you can not start your computer from the external hard disk, but you need to enter it to copy or backup the important files or reinstall the system, so you need to enter it from the USB flash drive, it can help you do many thing. But at first, you need set your system reboot from USB flash drive.
Here use the MSI Military Class 4 Motherboard as the example.
Step 1: Insert the USB Flash Drive into the computer USB port.
Tips: You need do this first. I think this will be more easily and convenient to test if you have already setup it. If your USB Flash Drive supports USB 3.0, you can try to insert the blue port.
Step 2: Restart your computer and press the "Delete" key to enter BIOS settings interface, and you can also press the "F11" key directly enter the reboot menu.
Tips 1: The different brand computers had different keys to enter the BIOS. For example, the Lenovo laptop and desktop BIOS shortkey is "F12", HP computer use "F9" and Dell use "F12", etc.
And some DIY computers use "F8" as the BIOS settings interface key.
Tips 2: If these are not work and you do not want to use Goolge to search it, you can try to press all "F" keys by your two fingers after your restart the computer. In my mind, I think this is the easiest way. I don’t care which one is the really one I should press, I press all.
Step 3: Choose the "SETTINGS" menu by using left mouse or direction key + "Enter" key combination.
Step 4: Choose the "Boot" item.
And you will see the interface and the boot order priorities.
Here you can see the "Boot Option #1 is UEFI Hard Disk", it means the computer will reboot from the external hard disk.
Step 5: Location to the "Boot Option #1" and press "Enter" key to reset the reboot device.
Here you will find your USB Drive name, and you can choose it as the defaut reboot device.
Step 6: Return to the MSI BIOS interface, and choose the last one item "Save and Exit", and the computer will reboot from USB Flash Drive.
So after you setup USB Drive as the reboot device, restart it and it will enter your PE system to backup your computer data, partition the hard drive, recovery the system or clean install the system again.