Operating systems and some apps can be run from, and be installed from a USB drive. You do not need to boot to a desktop OS to access apps that can run from the bootloader of a computer. Likewise, if you need to install a new OS or perform a clean install, you will likely use a USB drive to install it.
Getting a system to ignore the installed OS, and boot from a USB isn’t hard if you know what setting needs to be changed and how to access it.
Boot from USB
To boot from a USB, you need to
- Boot to BIOS/UEFI
- Change the first boot device to USB
- Restart the system
The above is a basic rundown of what you need to do to boot from a USB but we’re going to go into more details because it gets a bit complicated. These directions DO NOT apply to a Mac of any kind.
1. Boot to BIOS/UEFI
In order to boot to BIOS, you need to;
- Turn the system off and turn it on again (or restart if you’re on a desktop OS).
- Tap the F2 or the F10 or the Delete key as the system is starting up to boot to your BIOS/UEFI. If you’re not sure which key to tap, check our post on how to access BIOS.
- You will see a basic windowless menu with tabs.
2. Check for BIOS/UEFI
You now need to determine if you’re running BIOS or UEFI. The method for selecting the first boot device will differ based on what firmware interface type you have.
- Boot to BIOS/UEFI (see previous section).
- Go to the Boot tab (or similar).
- Look for Legacy Boot or Secure Boot.
- If Legacy Boot is enabled, you’re running BIOS. If Legacy Boot is disabled, you’re running UEFI. Likewise, if you see Secure Boot and it is enabled, you’re running UEFI. If Secure Boot is disabled, you’re running BIOS.
3. Change Boot order – BIOS
Assuming you’re running the BIOS firmware type, follow these steps to change the boot order for the system.
- Boot to BIOS.
- Go to the Boot tab.
- Look for Boot Order (or similar), and select it by tapping the Enter key.
- Use the arrow keys to select USB disk or USB drive.
- Save the change and exit BIOS.
- Connect the USB drive you want to boot from to your system.
- Turn the system on and it will boot from BIOS.
4. Change Boot order – UEFI
Changing the boot order in UEFI is slightly different than changing it in BIOS.
- Connect the USB to your system.
- Turn your system on and look very closely at the boot screen. You will see options for different keys you can tap. One of those will be ‘Boot Options’. Tap the key associated with it.
- You will see a boot menu with options to select a boot device. The USB drive (or whatever is burned to it), will be listed there.
- Select it and your system will boot from the USB.
UEFI isn’t as common as BIOS, yet. Most people don’t know which they’re running and expect UEFI to act exactly the same as BIOS which is why it’s sometimes difficult to change the first boot device. With UEFI, the boot device is set to the HDD or SSD unless it is changed on startup whereas on BIOS, it follows an order of devices regardless if all of them are available or not.