Whether you're using a desktop computer or a laptop, your computer's motherboard contains an integrated battery. Unlike a standard laptop battery, the motherboard's battery doesn't power your computer while you're using it. Quite the opposite, actually the battery is tiny and only active when you're not actually using your computer.
The motherboard's battery is used for low-level system functions like powering the real-time clock and storing a computer's BIOS settings. On newer computers, the battery may only be used for the clock.
