Sometimes, you need to boot (this means "start") your computer from a CD/DVD or a USB drive. For example, when Windows does not start properly, or when you need to check if your computer random access memory (RAM) is working fine.
Most modern computers are set to boot from a hard disk drive or SSD. This is often required by the Secure Boot feature introduced with Windows 8. To boot from another drive, you might need to enter your device's UEFI or BIOS setup and disable Secure Boot temporarily. If the device has the CSM (Compatibility Support Module) setting in BIOS/UEFI, you need to enable it first.
To boot from a CD/DVD or a USB drive, you must insert or connect the media first and then restart or turn on your computer.
Using boot menus for one-time boot device selection
Many computers allow choosing the boot device without entering BIOS/UEFI by pressing the F8 key before Windows (or any other operating system) starts, but the most common ones are F9 on HP, F10 on Sony, F11 on MSI, F12 on Lenovo, Dell, and Acer, and ESC on ASUS.
Many Lenovo Y-series notebooks/IdeaPads have a small Novo button (half-round arrow pointing to down left) to the left of the Power button: on these devices, perform a complete shutdown first, then press and hold down the Novo button until your device starts and then use the startup menu to access the BIOS/UEFI setup.
Older Lenovo/IBM ThinkPads have a blue ThinkPad button for getting into the startup menu.
To boot most Windows 8, 8.1, or 10 tablets from a USB drive, turn the device completely off first. Connect your USB stick or external drive, hold down the Volume Down or - button, then press the Power button once.
Let's see some examples of quick boot selection options.
Dell computers always display the "F12 Boot Options" message on the top right of the screen for a few seconds, so you have to act quickly and press the F12 key. Pressing it more than once does not hurt.
Now you can use arrow keys to navigate in the menu and press Enter to boot your PC from the selected device.
Please note that you have to plug in your USB stick or drive before restarting or turning on your PC to see the USB Storage Device option. This applies to all computers, not only Dells.
Next, let's see a Lenovo ThinkPad L560 example (UEFI boot enabled). First, you need to press Enter to get to the Startup Interrupt Menu.
In the menu, press the F12 key to choose a temporary startup device.
Boot Menu appears, use arrow keys to choose the desired boot device and press Enter to start your device from it.
And here is an example of a desktop computer with an MSI motherboard. The boot menu keyboard shortcut is listed on the bottom right for a few seconds, so press F11 to select a temporary boot device.
Again, use arrow keys to navigate and press Enter to confirm your choice.
Changing boot order in BIOS or UEFI
To set boot priority to a CD/DVD or a USB drive, you must insert or connect the media first and then restart or turn on your computer.
You have to use a system setup utility to change the boot order permanently. Most modern PC-s have EFI (Extensible Firmware Interface) or UEFI (Unified Extensible Firmware Interface) setup for this. Older versions are called BIOS (Basic Input/Output System) setup or CMOS (Complementary Metal-Oxide-Semiconductor) setup, or Setup Configuration Utility/SCU.
You can access the setup utility by pressing one or more keys on your keyboard before your operating system (Windows, Linux, etc) starts. As there are very many different computer manufacturers, these keys or combinations are different, but they are almost always displayed on the screen. These shortcut keys are also in the manual that came with your computer.
The most usual keys are F1, F2, F10, F12, and Del (aka Delete). On some computers, you might have to press the Esc key first to see the options list.
Many Lenovo Y-series notebooks/IdeaPads have a small Novo button (half-round arrow pointing to down left) to the left of the Power button: on these devices, perform a complete shutdown first, then press and hold down the Novo button until your device starts and then use the startup menu to access the BIOS/UEFI setup.
Older Lenovo ThinkPads have a blue ThinkPad button for getting into the startup menu.
To access UEFI on most Windows 8, 8.1, or 10 tablets, turn the device completely off first. Hold down the Volume Up or + button, then press the Power button once. When a logo (for example, Surface) appears, release the Volume Up button.
Please do not change any other settings than boot order or Secure Boot! BIOS/UEFI setup utility is a very powerful program and you can make your computer inoperable when you mess around with it!
Let's see some examples again.
Example one - Dell Latitude laptops with Legacy and UEFI boot mode
Dell does not display the BIOS/UEFI access key at startup, so press the F2 key several times while the Dell logo is displayed.
Expand the General section from the top left and click the Boot Sequence. Arrow keys and Enter work as well. In the Boot Sequence section, you can tick or untick device types on the left to enable or disable booting from these. To change device priority, click its entry on the right so that the item becomes highlighted (changes to blue) and then use Up and Down buttons or PgUp and PgDn keys to move the entry up or down in the list. Finally, click Apply at the bottom of the screen. The example below is for Legacy or BIOS boot mode - this is specified in the Boot List Option section.
Below is an example of Dell Latitude E6410 with UEFI boot mode. It is designed exactly the same as in the example above, so photos have been heavily cropped. These older Latitude devices do not support Secure Boot, so there is nothing to disable here.
If you connect a device that supports UEFI boot before turning on your PC, it is automatically detected by the Dell UEFI setup. Just tick the device's checkbox to add it to Boot Sequence. If necessary, move it to the top of the boot sequence list using arrow buttons on the right. Click Apply and restart your computer.
Please do note that not all bootable devices support UEFI mode. The example here is for Windows 10 Recovery Drive, but the very same USB stick would not be listed here if it had something without UEFI boot support on it.
You can, however, add a UEFI boot device manually in Dell and most other UEFI setups. This does not guarantee that your computer will actually boot from the manually added device, but sometimes it is worth trying.
Click the Add Boot Option button. Other manufacturers might name it Add or Add new boot device, or something similar.
If you see multiple entries in the File System List, you are in luck. USB drives (both pen drives and external hard drives) always have USB written somewhere, CD/DVD readers always have CD or DVD in device description. This helps you to distinguish between multiple entries. You should never select entries with RAID, HDD, or SSD written in them - this is most probably your system drive (the one where Windows is installed).
Fill in the Boot Option Name field (this is just a description - USB recovery, for example) and choose the USB drive or CD/DVD drive in from the File System List. The File Name field should be empty for all CD-s and DVD-s, and for most USB drives that actually do support UEFI boot.
Click OK.
Back in the UEFI setup, Boot Sequence, click a device on the right, and use arrow buttons to move its entry up or down. Click Apply and restart your PC to test the new boot order.
Here's another Dell Legacy/BIOS example, but from an older Latitude D630. This laptop does not support UEFI boot at all. The Boot Sequence option is in the System section. Use arrow keys to navigate and Space to enable or disable a device type. To change a device type priority, use U and D keys for moving the item up or down. Finally, press Enter to confirm changes.
Please do remember to revert the above settings back to their defaults after troubleshooting, otherwise, Windows might fail to boot.
Example two - Lenovo ThinkPad in UEFI boot mode and the CSM setting
For a modern Windows device, here's Lenovo ThinkPad L560 with Secure Boot support.
Press Enter while the Lenovo logo is displayed to get to the Startup Interrupt Menu.
In the menu, press the F1 key to launch BIOS Setup Utility (note that it is called so even in the UEFI boot mode).
As usual, navigation help is displayed on the bottom of the screen, and item-specific help/description appears on the right.
To disable Secure Boot, use the arrow keys and the Enter key to open the Security menu and go to the Secure Boot entry. Set Secure Boot to Disabled and press the ESC key twice to get back to the main menu.
Move to the Startup menu, set UEFI/Legacy Boot to Both, UEFI/Legacy Boot Priority to UEFI first, and CSM Support to Yes.
Then move to the top and open Boot.
In the Boot Priority Order list, select your desired boot device (USB or CD drive) with arrow keys and move it above the Windows Boot Manager entry by pressing the + key repeatedly.
Press F10 to save changes and restart your device.
Please do remember to revert the above settings back to their defaults after troubleshooting, or Windows might fail to boot.
Example three - Lenovo desktop in UEFI mode and the CSM setting
Let's see another Lenovo example, this time an S510 desktop with CSM (Compatibility Support Module). First, remember to connect your bootable USB drive before turning on your computer.
As you can see from the bottom left of the screen, you need to press the Enter key to access the startup menu.
As this computer has the CSM setting and Secure Boot setting on different tabs, move to the Startup tab, and set CSM to Enabled. On this device, this automatically disables the Secure Boot option in the Security tab, but it never hurts to double-check if Secure Boot has been turned off.
Next, move up and open the Primary Boot Sequence sub-menu.
You should see your USB drive in the lower part of the list (yours might have a different name), use arrow keys or mouse to activate it. Then press the + key multiple times to move it to the top of the list.
If you want to boot from a CD or DVD instead, move the CD/DVD drive (HL-DT-ST DVDRAM in this example) to the top of the boot sequence list.
Press the F10 key to save changes and restart your computer.
Please do remember to revert the above settings back to their defaults after troubleshooting, otherwise, Windows might fail to boot.
Beware that disabling the CSM setting does not automatically enable Secure Boot on this particular device! You need to move to the Security tab, open the Secure Boot sub-menu, and enable Secure Boot. Again, press F10 to save your changes.
Example four - MSI desktop in Legacy/BIOS boot mode
Back to the computer with MSI motherboard. As shown on the startup screen, you need to press the Del key to access the BIOS setup.
This motherboard has full UEFI support, but it is in the Legacy/BIOS boot mode. You can quickly change boot order just by dragging the device type icons on top of the screen. Icons with the letter "U" indicate UEFI boot order, others are for legacy/BIOS boot order.
You can also do this the old-fashioned way, just click Settings on the left (see screenshot above) and then click Boot in the Settings list.
Here you can use the arrow keys to navigate, the Enter key to choose an item, and +/- keys to move the chosen item up or down in the list. Press the Esc key after you are done, and then choose Save & Exit from the Settings list.
Example five - older Gigabyte desktop
Here's an older desktop PC with a Gigabyte motherboard. It has no support for UEFI boot or Secure Mode.
To change the boot order permanently, you will have to press the Del key on your keyboard to access the BIOS setup.
Use the arrow down key to select Advanced BIOS Features, then press the Enter key once.
As you can see, First Boot Device is CDROM, Second Boot Device is Floppy and Third Boot Device is Hard Disk. Use arrow keys to navigate and press Enter to select an item. Then use + and -, or PgUp and PgDn keys (short for Page Up and Page Down keys) to change the value of the selected item.
Please note that the USB device type is not listed in this example. To boot this computer from a USB stick or hard drive, navigate to the topmost item, Hard Disk Boot Priority, press Enter and change the order of listed drives there (again, the USB device has to be plugged in already).
Press the F10 key to save changes. You will then be asked if you want to save changes and exit (this means restart), press the Y key, and then press Enter.
Example six - an old no-name laptop
This old laptop with a motherboard by Insyde displays a full-screen logo with shortcut keys on the bottom left. As expected, it has no support for UEFI boot.
Press the F2 key while this logo is displayed to access the BIOS setup.
Some letters are red in the top menu, this means that you can open the menu by holding down the Alt key and pressing the red letter key - for example, you can open the Boot menu by pressing Alt+B.
Open the Boot menu, use the arrow down key to select Boot Sequence, and then press the Enter key:
Press the Tab key twice to activate device type selection. Move to a device type with arrow keys, then use PageUp and PageDown keys to move it up or down in the list. Press Enter confirm changes.
As there is no entry for USB devices, you must choose the HDD Sequence (Alt+H) from the Boot menu and use the same keys to change the boot sequence there.
Open the Exit menu by pressing Alt+X on your keyboard, choose Save and Exit with down arrow key and press Enter twice to save new configuration and restart your computer.
I hope these examples gave you enough information to change the boot order on your computer. 