Why Do Motherboards Have Batteries?

The video explains why motherboards still include a lithium coin battery. It starts by noting the presence of a small battery on most boards and explains that its historical purpose was to power a CMOS chip that stored BIOS settings. The host clarifies that CMOS stood for a common semiconductor type and was traditionally volatile, meaning settings would be lost when power was removed. To prevent this, a battery was included to keep the clock and essential data alive during power outages or unplugged periods. As technology evolved, BIOS storage moved from simple CMOS to non-volatile RAM with higher capacity, but the battery remains to maintain timekeeping, similar to a wristwatch powered by a battery. The video also touches on server practices, where time is often obtained via network time protocol at boot rather than relying on a local CMOS battery, but for home PCs the battery continues to play a useful role. Finally, it covers easy BIOS reset options like clear CMOS buttons and notes that, in practice, CMOS batteries last for years and do not require frequent replacement, making them a largely maintenance-free feature for most users.

Topics · technology · computer_hardware · timekeeping · BIOS · motherboard