My HP ProLiant DL380 G5 was restarted after resolving an RPC-related problem, but it now powers on without displaying POST, BIOS, or any video output. There is also no visible hard-drive activity. I have already disconnected power and drained residual charge, reseated the RAM, cleared and reseated the CMOS battery, reseated the RAID controller battery, and reseated all hard drives. The fans and DIMM status lights turn green, but the fans continue running loudly and the system never progresses to a boot screen. This server is still running production services, including the primary domain controller, and the backup domain controller has not finished replicating. What hardware checks should I try next?
4 Answers
A failed voltage regulator module (VRM), especially the one associated with the first processor, can cause this exact no-POST behavior on these systems. If the server has redundant processor VRMs, you may be able to swap them temporarily to test whether one has failed. Treat that only as a diagnostic step, though—the hardware is very old and should be replaced as soon as possible.
Green fan and DIMM lights only show that some parts are receiving power; they do not confirm that the CPU or motherboard is functioning. Try a minimum-hardware boot: disconnect the drive backplane, RAID controller, extra PCI cards, and any nonessential USB devices, then test with one processor and the minimum supported memory configuration. If it still produces no POST, suspect the VRM, processor, system board, or power supply.
Given the age of the DL380 G5, a sudden failure of the motherboard, VRM, power supply, or processor is unfortunately plausible. Avoid repeatedly power-cycling it for too long if the fans stay at maximum speed. Prioritize recovering the domain-controller services from the backup or another system while diagnosing this one.
Check the server status LEDs for an error pattern and see whether the integrated management controller is reachable. The Integrated Lights-Out logs or the Integrated Management Log may identify a processor, memory, power, or system-board fault. Since management was never configured, local LED codes and the hardware maintenance guide may be your best options.

The backup domain controller was configured, but replication had not completed before the primary failed. I am going to focus on checking the hardware fault indicators and recovering the directory services while preparing replacement hardware.