Summary
Both CPU1 and CPU2 power required to boot the server while using Single CPU also.
Description
Getting 1-5-2-1 and 1-5-4-2 POST Error Beep Code with single CPU
Resolution
Both the CPU1 socket and CPU2 socket need to have power connection even if a single CPU is installed on the board.
Additional information
In S2600ST family both the CPU sockets, CPU1 and CPU2 need to have 12V power connection mandatory as BMC monitors the power presence in order for the board to boot.
For more details, refer to the Technical Product Specification PDF found in the CPU Power Connectors section in the Technical Product Specification for the Intel® Server Board S2600ST Family.