Unified Extensive Firmware Interface(UEFI) is more or less a firmware that acts as a replacement for most Basic Input and Output System (BIOS) in many systems which have it at the Setup. It is a new firmware the UEFI group originally developed for intel and it has some history behind it that can be read online.
Image of UEFI logo
It brings about another way to boot Operating System(OS) that is different from the prevalent master-boot-record(MBR) process we are often used to in most computer systems.
To install non-UEFI operating system in a UEFI-mode system is to first putting off the firmware secure boot or disable it at the BIOS Setup. If you are interested in changing UEFI operating system that initially came with your system you'll need to go into the BIOS to make some changes. Before doing that in Windows 8 operating system, it is required to take to some process at the desktop environment first(as one of the easiest ways to make the changes).
When you are ready, boot up your system as usual and follow the instruction that follows.
Image of Windows 8 Settings
STEP 1: At your Windows 8 desktop move your mouse cursor to extreme right corner of your screen(close to your computer time and date below your screen) and click 'Change PC settings'.
Image showing General at PC setting in Windows 8
STEP 2: Select 'General' on the list of items at the 'PC Settings'.
Image of PC Setting with arrow pointing to Restart-now tab
STEP 3: To the right-hand side of the 'PC Settings' scroll down to 'Advanced Start-up' and click 'Restart now' tab.
Image of Choose an option screen in Windows 8
STEP 4: Under 'Choose an option' click 'Troubleshoot' to continue.
Image showing Troubleshoot screen in Windows 8
STEP 5: Click 'Advanced options' at the 'Troubleshoot' screen.
Image showing Advanced options screen in Windows 8
STEP 6: At the 'Advanced options' click on 'UEFI Firmware Settings' to continue.
Image showing UEFI Firmware Settings in Windows 8
STEP 7: Click on 'Restart' at the 'ÚEFI Firmware Settings' screen to restart your system.
Image showing red arrow pointing to F2 key
STEP 8: At boot quickly depress F2 key to enter BIOS or the BIOS Setup.
Image showing Secure Boot at BIOS
STEP 9: Under 'Security' look for 'Secure Boot' and change the mode to 'Disabled'.
Image showing Boot Mode at BIOS
STEP 10: Next click on 'Advanced' and change the 'Boot Mode' to 'CMS Mode' and press F10 to save changes.
After the process you can now start to install your non-UEFI operating system.
