Win8 - Accessing Boot Options
1. hold Shift while clicking Restart in the Shut Down menu to restart your computer into the boot options menu
2. In the PC Settings application, select the General category and click the Restart now button under Advanced startup. Your computer will restart and you’ll enter the Windows 8s boot options menu, where you can access the UEFI BIOS and change other setting
3. in a Command Prompt window to restart their computer directly into the boot options menu:
Shutdown.exe /r /o
NOTE: If you don’t see the UEFI Firmware Settings tile here, your computer doesn’t use UEFI. You’ll need to access the BIOS in the traditional way, by pressing a specific key during the boot-up process