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What are CMOS, BIOS, and UEFI?

Your PC is intricate system composed of numerous hardware and software components working beautifully together. Among these components, the BIOS plays a pivotal role in ensuring that your components talk to each other properly so your PC runs smoothly and efficiently. Understanding the BIOS and how it works is essential for anyone looking to set up or maintain a computer properly.

What are the CMOS and BIOS?

CMOS stands for Complementary Metal-Oxide-Semiconductor, but you can instantly forget that since it’s not important. What matters is that in PCs, it refers to a tiny chunk of battery-powered memory that stores your BIOS settings. This memory retains settings such as the system time and date, as well as the hardware configuration, even when the computer is turned off.

The BIOS, or Basic Input/Output System, is the firmware embedded in your motherboard. When you power on your PC, it’s the BIOS that runs first. Its primary function is to initialize and test the system hardware components before loading a bootloader for your operating system. The BIOS ensures that all the components in your machine, such as the CPU, RAM, GPU, and storage, are recognized and functioning correctly.

The BIOS is essential for booting up your system and providing the framework for your hardware to communicate with one another. It acts as an intermediary between the operating system and the hardware components of the computer. Without a properly functioning BIOS, your computer wouldn’t be able to start up or operate efficiently. Instead, it would just be a dumb collection of hardware that couldn’t communicate properly.

What Is a UEFI BIOS?

UEFI, or Unified Extensible Firmware Interface, is an updated version of the BIOS. It was introduced to overcome the limitations of the traditional BIOS, offering more advanced features, a more user-friendly interface, and faster boot times. UEFI supports larger hard drives, more partitions, newer technologies, and improved security features. It’s now the default for all new systems.

The UEFI BIOS also provides a graphical user interface with mouse support that is much easier to navigate than its predecessor. It supports Secure Boot, which helps protect the system from malware and unauthorized access during the boot process. (But also cause issues with the anti-cheat systems in some games) Additionally, UEFI can execute drivers and applications, making it a more versatile and powerful firmware compared to the traditional BIOS.

Like CMOS in the past, it’s important to keep your UEFI BIOS up to date. This not only ensures that your PC’s performance is optimal, but also makes sure that your machine supports the latest hardware and security. Motherboard manufacturers regularly release updates to address bugs, improve compatibility with new hardware, and enhance security features. Updating the UEFI BIOS can resolve issues related to hardware compatibility and performance and ensure that your system remains secure against vulnerabilities.

A good example of why you’d want to update your UEFI BIOS is to get the most from your memory. Properly configuring DRAM in the UEFI BIOS is vital to achieve optimal system performance. Incorrect DRAM settings can lead to system instability, crashes, and poor performance. Use the UEFI setup screen to configure the correct voltages, frequencies, and latencies for your memory. Many modern motherboards support Extreme Memory Profiles (XMP), which allow users to configure DRAM settings for optimal performance easily.

How you get into your UEFI BIOS depends on your motherboard, but hitting [Del] at boot up, or possibly [F2], [F10], or [Esc], usually gets you in.

Understanding CMOS, BIOS, and UEFI is fundamental for anyone looking to set up or maintain a PC. These components ensure that the hardware and software work together seamlessly, providing a stable and efficient computing experience. Keeping the UEFI BIOS up to date and correctly configuring DRAM settings are essential practices for achieving optimal system performance and reliability.