The BIOS firmware supports both Legacy BIOS and Unified Extensible Firmware Interface (UEFI) BIOS. The default setting is Legacy BIOS. Because the Windows Server 2008 and 2012 operating systems support both Legacy BIOS and UEFI BIOS, you have the option of setting BIOS to either Legacy BIOS Boot Mode or UEFI BIOS Boot Mode before you perform the installation.
Note - After you have the installed the Windows Server operating system, if you decide you want to switch from legacy BIOS to UEFI BIOS, or vice versa, you must remove all partitions and reinstall the operating system.
For example, to reset the server:
-> reset /System
The BIOS screen appears.
After a few moments, the BIOS Setup Utility appears.
The Boot menu screen appears.