If a computer forgets the date and time after being unplugged, the small CMOS battery is a common suspect. On many desktops this is a simple part, but the symptom can still create practical problems: wrong boot order, certificate errors, update failures, or repeated BIOS prompts.

On laptops, the situation can be less straightforward. Some models use internal batteries or board-level arrangements that should not be guessed at. A clock reset after liquid damage or a power fault may need more than a battery swap.

Check related symptoms

Does the computer ask you to press a key at every startup? Does it forget boot settings? Does Windows show security or browser certificate warnings? Does the issue only happen after the computer is unplugged from power?

These details help separate a simple CMOS issue from a firmware, motherboard or power problem.

Be careful with BIOS settings

Changing storage mode, secure boot or boot order without noting the original settings can make Windows fail to start. If the computer contains important files, avoid experimenting widely in firmware menus.

AEPC / AKL East PC can check BIOS, startup and motherboard-related symptoms for Auckland customers. Contact us with the device model and screen photos before changing settings.