Fujitsu BX630 - PRIMERGY - S2 Dual Operating Manual page 66

Server menu
Even if only one CPU is installed, the status indicators are
displayed for all possible CPUs. If Disabled is set for all the CPUs,
the system still starts with one CPU.
Re-enable Failed CPUs
Resets all CPUs flagged as Failed to Enabled.
66 Operating Manual
BIOS Setup
BX630 S2