8.5 UEFI settings Unified Extensible Firmware Interface (UEFI) is an interface that takes care of handing over the pre-boot environment to the operating system. UEFI is effectively the replacement for BIOS. BIOS has been around for many years but it was not designed to handle the amount of hardware that can be added to a server today. New IBM System x models, including the HX5, implement UEFI to take advantage of its advanced features. You access UEFI by pressing F1 during the system initialization process, as shown on Figure 8-31.