EMZETT.BIOS vs. UEFI
In short: BIOS and UEFI are both the motherboard’s firmware that checks hardware after power-on and starts the operating system. UEFI is the modern successor of the old BIOS and can do much more.
In more detail: The BIOS (Basic Input/Output System) dates from the 1980s, runs in 16-bit mode, uses text menus and boots via the Master Boot Record (MBR). UEFI (Unified Extensible Firmware Interface) is a small operating system of its own with 32/64-bit code, a graphical interface, mouse, network and drivers. It boots via GPT and an EFI system partition.
In Depth
| BIOS (legacy) | UEFI | |
|---|---|---|
| Age | 1981 | from about 2005, standard since Windows 8 |
| Processor mode | 16-bit | 32/64-bit |
| Partition table | MBR (max. 2 TiB per disk, 4 primary partitions) | GPT (up to 9.4 ZB, 128 partitions) |
| Interface | text, keyboard only | graphical, mouse possible |
| Boot speed | slower | faster (fast boot) |
| Security | none | Secure Boot, signed drivers, TPM integration |
| Drivers | fixed option ROMs | loadable UEFI drivers (firmware drivers) |
| Settings storage | CMOS (battery) | NVRAM (flash) |
- Settings: Press Del, F2 or F10 at startup. Boot order, Secure Boot, XMP memory profiles and virtualization live there.
- CSM (Compatibility Support Module): A UEFI mode that imitates a BIOS so old systems boot. Windows 11 requires UEFI with Secure Boot, so CSM off.
- Switching: Converting Windows from MBR to GPT works with
mbr2gpt, without reinstalling. Afterwards set UEFI mode in the firmware. - Colloquially: Many say “BIOS” even for UEFI (“go into the BIOS”).
See also: BIOS, UEFI, GPT (GUID Partition Table), MBR (Master Boot Record), CSM (Compatibility Support Module)