Method I: Tapping the Keyboard
Note that we used an Acer Aspire V5
1. Start or restart the machine while tapping the F2 key
> Enter the UEFI Setup menu
2. On the top menu, select “Security”
> Enable the UEFI password by creating a password
> The act of entering a password enables or arms the following features
3. Find and disable “Secure Boot”
> On some makes & models, you may have to find and disable “CSM” //see notes below; ignore & override all warnings
4. On the top menu, select “Boot”
> Point to and click on “UEFI” BIOS mode to disable it and enable legacy BIOS
5. Change boot order
> Give priority to the device of your interest
6. Find the option to enable the F12 key
> Enable the tapping of the F12 key for interruption to the boot order
7. F10 to save the new settings, exit and restart
> The system should boot from the device given priority
9. If not, restart while tapping F12
> Pick the device you want to boot from

Method II: Using Windows 8 Itself
1. Startup Windows 8 as normal to the Welcome Screen
2. Hold down the Shift key
3. Navigate to the Shutdown icon and select “Restart” while still holding down the Shift key
4. Windows 8 will boot into “repair” options
> Select “Troubleshoot”
5. Select “Advanced” > “Startup Settings” > “UEFI…” > “Restart”
6. Go to Method I step 2 and run through the steps

– Windows 8 family of operating systems are designed to boot within 200 millisecconds
– It is incredibly difficult to interrup the Windows 8 bootup process because of the 200 ms time frame and the new security mechanisms known as “Secure Boot” and “CSM”
– You must disable “Secure Boot”, the new industry standard that ensures only trusted software / with approved signatures run on class 2 and 3 computers
– Another issue that make it impossible to interrupt the start up of Windows 8 family of operating systems are Solid State Drives
– Each manufacturer implements “Secure Boot” and “CSM” differently, which means the features/buttons to control these operations may vary in how they are featured on the UEFI menu.

Further reading from Microsoft:
– Secure Boot requires a PC that meets the UEFI Specifications Version 2.3.1, Errata C or higher.
– Secure Boot is supported for UEFI Class 2 and Class 3 PCs.
– For UEFI Class 2 PCs, when Secure Boot is enabled, the compatibility support module (CSM) must be disabled so that the PC can only boot authorized, UEFI-based operating systems.
– This may be the reason why you may not have to disable the “CSM” at all [because it is already disabled from factory for class 2 computers].