The Basic Input-Output System (BIOS), also known as Legacy BIOS, is a program stored in a small chip within the motherboard. Its primary function is to identify and initialize key components such as the processor, memory, hard drives, optical drives, and other hardware. The BIOS settings, which can be modified by the user, are stored in a small amount of RAM located on a Complementary Metal-Oxide-Semiconductor (CMOS) chip. This CMOS RAM retains its information even when the power is turned off, thanks to a small battery on the motherboard. Essentially, BIOS controls your computer from the moment you turn it on until the operating system takes over.
On the other hand, the Unified Extensible Firmware Interface (UEFI), sometimes referred to as UEFI BIOS, is an interface that was developed by Intel. Over time, it has come to replace the traditional BIOS that has been used in computers since 1981. In the case of UEFI, these settings are stored in Non-Volatile Random Access Memory (NVRAM), which also retains its information after the system is powered off. Most UEFI firmware implementations continue to support BIOS services through a feature known as the Compatibility Support Module (CSM).
While BIOS and UEFI serve similar purposes, they are not the same. However, the terms are often used interchangeably due to their overlapping roles in system booting processes. It’s important to note that both BIOS and UEFI use a form of non-volatile memory (CMOS for BIOS, NVRAM for UEFI) to store their settings.
What is CMOS?
The Complementary Metal-Oxide Semiconductor (CMOS) is a type of battery-powered chip embedded within computers. It’s also known as the Real Time Clock (RTC) or Non-Volatile Random Access Memory (NVRAM). The primary role of CMOS in computers is to preserve crucial BIOS settings and configurations, such as the date, time, boot sequence, hardware settings, and password information. This data is stored in a small battery-powered chip on the motherboard, commonly referred to as the CMOS battery.
How To Clear CMOS / Reset BIOS Settings?
Resetting the CMOS settings, which are essentially the BIOS settings, involves a few steps. First, you’ll need to unplug the computer from the power source and open the case. Next, locate the small, coin-shaped battery on the motherboard, typically labeled as CR2032 or similar. Remove this battery and leave it out for about 5-10 minutes. Afterward, reinsert the battery, close the case, and reconnect the computer to the power source. Upon restarting, the BIOS settings should have reverted to their default values.
To access the BIOS or UEFI interface, you typically need to press a specific key on your keyboard. This key can vary based on the manufacturer and the specific product. As soon as you power on your computer, you should start pressing this key repeatedly.
When your computer starts up, the BIOS performs a process known as the Power-On Self Test (POST). It is during this POST stage that you should press the designated key to enter the BIOS. If you press the key after the POST stage, the computer will continue to boot normally.
If done correctly, your computer should quickly display the BIOS or UEFI interface. However, some computers complete the POST process so quickly that they might not register the key press in time. In such cases, users may need to use alternative methods to access the BIOS/UEFI. For example, in Windows, you can access the UEFI settings and disable the Fast Boot option. This allows for direct access to the BIOS/UEFI during subsequent startups.
ASUS
- PCs / ASUS - F2
- Motherboards / ASUS - F2 or DEL
MSI
- PCs / MSI - Del
- Motherboards / MSI - DEL
Gigabyte / Aorus
- Aorus / Gigabyte - F2 or DEL
ASRock
- ASRock - F2 or DEL
NZXT
- Motherboards / NZXT - F2 or DEL
EVGA
- Motherboards / EVGA - DEL
BIOSTAR
- Motherboards / BIOSTAR - F12
HP
- HP - ESC or F10 or F1
- You may need to press ESC Then F10
Dell
- Dell - F2 or F12
Acer
- Acer - F2 or DEL
Lenovo
- Desktops / Lenovo - F1
- Laptops / Lenovo - F2 or Fn + F2 or Novo Button
- ThinkPads / Lenovo - Enter + F1
Toshiba
- Toshiba - F1 or F2 or F12 or ESC
Compaq
- Compaq - F10
Sharp
- Sharp - F2
Intel
- Intel - F2
Sony
- Sony - F1 or F2 or F3
- or Assist Button (Use the Assist Button when the computer is off, not when it is booting).
Samsung
- Samsung - F2 or F10
Fujitsu
- Fujitsu - F2
ECS
- ECS - DEL
Origin PC
- Origin PC - F2
Zotac
- Zotac - DEL
GATEWAY
- GATEWAY - F2 or DEL
eMachines
- eMachines - Tab or DEL
NEC
- NEC - F2
Packard Bell
- Packard Bell - F1 or DEL
Microsoft Surface
- Surface Pro 1-3 - Press and hold volume down button.
- Surface Pro 4 & Book - Press and hold volume up button.