A systems administrator is troubleshooting a rackmount server that failed to restart properly following a planned power outage. Upon connecting a monitor, the administrator notes the system date has reset to its manufacturing default and the boot order is incorrect, causing a boot failure. Attempts to correct the settings in the UEFI/BIOS are lost after each power cycle. Which of the following is the MOST likely cause of these issues?
The CMOS battery has failed.
The RAID controller cache battery needs replacement.
The correct answer is that the CMOS battery has failed. The Complementary Metal-Oxide-Semiconductor (CMOS) battery provides constant power to the motherboard to retain system settings such as the system time, date, and hardware configuration (including boot order) stored in the UEFI/BIOS. The symptoms described - a reset system clock and the loss of boot order settings after a power cycle - are classic indicators of a failed CMOS battery. A faulty PSU would likely prevent the server from powering on at all or cause random shutdowns, but it would not specifically erase saved BIOS settings. A failed RAID controller cache battery would affect the storage array's performance or integrity but would not impact the system's main clock or general BIOS settings. A corrupted BIOS might prevent the system from booting entirely or display different error messages, but the ability to enter setup and make changes that are subsequently lost points specifically to the component responsible for retaining those settings: the CMOS battery.