BIOS (Basic Input Output System) and CMOS Battery

• The BIOS chip is installed on the motherboard by default
• It is going to detect hardware in your computer
• BIOS detect CPU, RAM , Hard disk drives, DVD drives, NVMe , SSD , Cache memory
• It detects if you have a connected keyboard, mouse or not connected

CMOS Battery [Complementary Metal Oxide Semiconductor]:

What it powers

• It provides power to the BIOS firmware even when your computer is turned off.
• The BIOS stores system settings, such as boot sequence, hardware configuration, and most importantly—date and time.

Why CMOS battery is Important

• Without this battery, your PC would "forget" the date, time, and BIOS settings every time it's turned off.
• It allows smooth startup by retaining the correct hardware configuration.

Lifespan of CMOS battery

• Usually lasts 3 to 5 years, depending on usage and environment.
• CMOS battery voltage is 3.0 Volts.
• If voltage drops below 2.6Volts, then you must replace it with a new CMOS Cell.