Shelby

Shelby Meyer

Written September 30, 2024
AI Enhanced January 17, 2025
Updated September 22, 2025
Category [EDUCATION]

#0012 What is the BIOS/UEFI?


BIOS screen

Basic Input Output System (BIOS)

The BIOS is a chip on your computer's motherboard. It’s programmed with special software called firmware that controls the basic functions of your computer. The BIOS keeps track of what hardware is inside your computer, including things like the processor (CPU), memory, hard drive, USB ports, fans, and even the system clock. It also has default settings, but you can adjust them to customize how your computer works. On basic motherboards, there might only be a few settings to change, using a text based interface.

Unified Extensible Firmware Interface (UEFI)

The UEFI is an updated version of the BIOS, providing support for faster boot times, larger drives, and improved security. You will also find new features such as TPM and Secure Boot. UEFI typically offers a more modern user interface with numerous configuration options. The terms BIOS and UEFI are sometimes used interchangeably.

P.O.S.T.

When you power on your computer, the BIOS runs first. It performs a test called POST (Power-On Self-Test) to make sure everything is working correctly. If something’s wrong, you’ll see an error message. If everything passes, the BIOS checks the boot sector of the hard drive to find the operating system (like Windows or Linux) and load it. The BIOS also uses a small battery to keep the system clock running and remember your settings. This whole process happens quickly, before your operating system fully takes over.

BIOS Updates

The firmware in the BIOS doesn’t usually need updates, but sometimes it’s necessary to fix bugs, add new features, or support newer processors. It’s important to only update the BIOS if you’re having problems, because updating it incorrectly could seriously damage your computer. Interrupting the update could also cause problems, so be careful if you decide to do it. Consult your manual or the manufacturers website for instructions.

BIOS Flashback

Some motherboard have a feature called BIOS flashback. If a BIOS update fails or becomes corrupted; you can use BIOS flashback. This will revert the BIOS back to the original version from the factory. Consult the manual or manufacturers website for instructions. Often times this feature can even be used without a processor installed. Some boards will even have 2 copies of the BIOS on board so the user can switch between them as needed.

Fan Curves

High-quality motherboards provide users with the ability to configure individual fans within the system, including CPU, case, and radiator fans. These fans can be managed through either voltage control or PWM (Pulse Width Modulation). Gamers may prefer a more aggressive cooling profile for improved performance, whereas office users might prioritise quieter fan operation. Fan speeds are typically regulated by the temperature sensors integrated into the motherboard and processor.

BIOS fans

Processor Overclocking

Overclocking means adjusting the BIOS settings to make your CPU run faster than usual. This is something gamers often do to boost performance and get a small advantage over others. This assumes the processor and BIOS support the overclocking feature.

More:
Additional information on processors can be found in Blog Posts #42, #58, and #60.

Memory Overclocking

Your BIOS may have the option for memory overclocking This is typically found on gaming computers. You can enable DOCP or XMP which will allow the memory to perform faster. This assumes the memory in the computer supports the overclocking feature.

More:
Additional information regarding memory can be found in Blog Posts #28, #64, #65 and #67.