A user reports that, despite manually changing the date and time on a computer, the...

The CMOS battery powers the real-time clock (RTC) on the motherboard, which maintains the date and time when the computer is turned off. If the battery fails, the system will lose date and time settings, reverting to defaults on restart.

Why Not A (OS updates): While OS updates can sometimes cause time issues, they don’t typically affect changes persisting after shutdown.

Why Not C (NTP server): An incorrect NTP server setting would cause the system to synchronize incorrectly, but this issue relates to time resetting during power-off.

Why Not D (RAM): RAM is volatile memory and unrelated to storing persistent time settings.

CompTIA A+ Exam Reference: Core 1 (220-1101), Section 3.4, motherboard troubleshooting​.