What Is BIOS Boot Order?
BIOS boot order is the list your computer follows to decide which device it should start from first, such as your internal hard drive, a USB flash drive, or a DVD. Every time you power on your PC, the BIOS checks this list in order and boots from the first device it finds that has a working operating system or bootable files.
This guide is for anyone trying to boot from a USB drive, reinstall Windows, run a repair tool, or fix a computer that will not start normally. If you have ever seen “Reboot and Select Proper Boot Device” or tried to boot from a USB stick that your PC ignored, this is the setting that controls that behavior.
How Does BIOS Boot Order Work?
The BIOS checks each device on your boot list, one at a time, until it finds one it can start from. If your hard drive is listed first and it contains Windows, your PC boots straight into Windows every time. If you want to boot from something else, like a USB installer, that device needs to come first on the list, or you need to trigger a one-time boot menu.
Here is the process in plain terms:
- You turn on the computer.
- The BIOS runs a quick hardware check called POST (Power-On Self-Test).
- The BIOS looks at the boot order list stored in its memory.
- It tries each device in that order until one successfully loads an operating system.
- Your PC boots into that device’s operating system or program.
If none of the listed devices are bootable, you get an error like “No Bootable Device Found.”
Why Boot Order Matters
Boot order matters because it decides what loads when you turn on your computer, and getting it wrong is one of the most common reasons a USB installer, recovery drive, or second operating system fails to start.
A few real situations where this setting matters:
- Installing Windows or Linux from a USB drive. If your hard drive is still first in line, the installer never loads, even if the USB stick is plugged in and working.
- Running antivirus or recovery tools from a bootable disc or USB. Same issue: the BIOS needs to check that device before the hard drive.
- Dual-booting two operating systems. Boot order (along with your boot manager) decides which OS loads by default.
- Network booting (PXE boot). IT teams and gamers setting up diskless systems rely on boot order to pull the OS from a network server instead of local storage.
Default Boot Order Explained
Most modern PCs are set at the factory to boot from the internal drive first, since that is where the operating system already lives. On a fresh Windows or Mac system, the default order usually looks something like this:
- Internal SSD or hard drive (with the OS installed)
- USB devices
- Optical drive (CD/DVD, if the PC has one)
- Network boot (PXE)
You will not need to touch this default order unless you are installing a new OS, running a repair tool, or troubleshooting a boot failure.
How to Change BIOS Boot Order (Step-by-Step)
To change the boot order, restart your PC, enter the BIOS or UEFI setup using the correct key for your brand, move to the Boot tab, and reorder the devices before saving and exiting.
Here is the full walkthrough:
Step 1: Restart your computer. Save your work and restart, rather than shutting down completely. You need to catch the BIOS prompt right as the system powers back on.
Step 2: Press the BIOS entry key repeatedly as it boots. The key depends on your manufacturer:
- Dell: F2 or F12
- HP: F10 (sometimes F2 or F6)
- Lenovo: F1 or F2
- ASUS: F2 or Delete
- MSI: Delete
- Acer: F2 or Delete
- Custom-built PCs: usually Delete
If Windows loads before you catch the prompt, restart and try again, tapping the key faster.
Step 3: Open the Boot menu. Once inside BIOS or UEFI setup, look for a tab labeled Boot, Boot Order, or Boot Sequence. Some systems place this under an Advanced or Startup menu instead.
Step 4: Reorder the devices. Use the arrow keys, plus/minus keys, or your mouse (on UEFI systems with a graphical interface) to move your preferred device, like a USB drive, to the top of the list.
Step 5: Save and exit. Look for a “Save Changes and Exit” option, usually triggered by pressing F10. Confirm when prompted. Your PC will restart and boot from the new first device on the list.
Faster alternative: use the one-time boot menu. Most PCs let you press a separate key, often F12, Esc, or F9, during startup to pick a boot device for that session only, without changing the permanent BIOS boot order. This is the quickest option if you only need to boot from USB once.
Common Boot Order Problems and Fixes
If your PC will not boot from a USB drive or shows a “no bootable device” error, the fix is almost always one of these four issues.
Problem: The PC skips the USB drive and boots to Windows anyway. The USB device is likely still below the internal drive in the boot order, or Secure Boot is blocking an unsigned installer. Move the USB drive to the top of the list, or temporarily disable Secure Boot in the BIOS security settings.
Problem: “No Bootable Device Found” error. This usually means the boot order list has no working device, or the drive itself lost its boot files. Check that your hard drive is detected in BIOS at all. If it is missing, the drive connection or the drive itself may have failed.
Problem: Changes to boot order do not save. This is often caused by a drained CMOS battery, which resets BIOS settings every time the PC loses power. Replacing the small coin-cell battery on the motherboard usually solves it.
Problem: BIOS setup screen never appears. Fast Boot settings in Windows or a very quick UEFI startup sequence can skip past the BIOS prompt window. Restart from the Windows Recovery menu instead (Settings > Recovery > Advanced Startup) and choose UEFI Firmware Settings.
Who Should Change Their BIOS Boot Order
You need to change your boot order if you are installing an operating system from a USB drive or disc, running a bootable diagnostic or recovery tool, setting up a dual-boot system, or troubleshooting a PC that will not start normally. If your computer already boots into Windows or macOS without issues, there is no reason to touch this setting.
FAQ: BIOS Boot Order
What is BIOS boot order in simple terms?
It is the order in which your computer checks connected devices, like your hard drive or a USB stick, to find one it can start from.
How do I get into BIOS to change the boot order?
Restart your PC and repeatedly press your manufacturer’s BIOS key (commonly F2, F10, F12, or Delete) before Windows loads.
Why won’t my PC boot from a USB drive?
The USB drive is probably listed after your internal hard drive in the boot order, or Secure Boot is blocking it. Move the USB to the top of the list, or check Secure Boot settings.
What is the difference between boot order and the one-time boot menu?
Boot order is a permanent setting that applies every time you start the PC. The one-time boot menu (often opened with F12 or Esc) lets you pick a device for a single restart without changing the saved order.
Do I need to change boot order to install Windows?
Yes, if you’re installing from a USB drive or DVD. Your USB or disc needs to be ahead of the internal drive in the boot order, or you can use the one-time boot menu instead.
Is changing BIOS boot order safe?
Yes. Reordering boot devices does not delete data or damage your PC. If something goes wrong, most BIOS menus have a “Load Default Settings” option to reset everything.
Why did my BIOS boot order reset on its own?
A drained CMOS battery on the motherboard is the most common cause. It resets BIOS settings back to factory defaults whenever the PC is unplugged or loses power for too long.
Dealing with other tech that’s acting up? See our guide on what a runtime environment is and how it works.
