Move USB to be first in the boot sequence.All available system devices will be displayed in order of their boot priority.

Using the arrow keys on your keyboard, select the BOOT tab.

When you enter BIOS Setup, the setup utility page will appear.(Depending on the company that created your version of BIOS, a menu may appear.) During the initial startup screen, press ESC, F1, F2, F8, or F10.Press the Power button on your computer.Start by plugging the thumb drive into a USB port. Otherwise, the computer will load from the hard drive as standard. If you're booting from USB media, you must change the BIOS boot order so the USB device is listed first. The boot order tells the machine which devices to search for the software needed to launch the computer and the priority of each device in that search. That's because the BIOS settings include the machine's boot sequence when starting up.

Starting your PC using USB rescue media is not difficult, although it first requires an adjustment in the BIOS (Basic Input Output System).

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