Video BIOS

It also implements INT 10h interrupt and VESA BIOS Extensions (VBE)[1][2] for basic text and videomode output before a specific video driver is loaded.

[3][4] Much the way the system BIOS provides a set of functions that are used by software programs to access the system hardware, the video BIOS provides a set of video-related functions that are used by programs to access the video hardware as well as storing vendor-specific settings such as card name, clock frequencies, VRAM types & voltages.

Unlike some other hardware components, the video card usually needs to be active very early during the boot process so that the user can see what is going on.

Ever since, EGA/VGA and all enhanced VGA compatible cards have included a Video BIOS.

[7] However, nowadays both NVIDIA and AMD digitally sign video firmware, which has made it impossible to make any changes to it.

Generic components of a graphics card. Note that the VGABIOS is a separate chip located on the graphics card, and not part of the GPU.
Practically all processing units require basic initialization, not just GPUs.