UEFI

The Unified Extensible Firmware Interface is the modern firmware environment used by current PCs. It initializes hardware, stores boot entries, supports GPT-formatted drives, and provides security features such as Secure Boot before Windows begins loading. You can open its settings from Windows through Recovery and Advanced startup, which is safer than guessing the startup key. Device-related options for storage modes, integrated graphics, virtualization, and platform security often live here, so an incorrect setting can make hardware disappear from Windows even when its software is installed. Record current values before changing anything, avoid switching storage-controller modes on an existing installation without preparation, and install firmware only for the exact system model.