Troubleshooting Power Issues

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If your server does not power on, the cause of the problem might be server AC power connections or power supplies (PS0-3).

In maximally configured systems, it is possible that the worst-case power consumption of the system could exceed the capacity of a single PS. The PSs provide an over-subscription mode, which allows the system to operate with fault-tolerance even with modest excursions beyond the rated capacity of a single PS. This over-subscription support is accomplished using hardware signaling between the PS and motherboard circuitry, which can force the system to throttle processor (CPU) and memory power in the event that a PS is lost. The resulting power savings will be enough to allow the system to continue to run (in a lower-performance state) until the power problem is resolved.

If your server does not power on, use the information in the following table to troubleshoot the issue.

Power Issue	Description	Action	Prevention
AC Power Connection	The AC power cords are the direct connection between the server power supplies and the power sources. The server power supplies need separate stable AC circuits. Insufficient voltage levels or fluctuations in power can cause server power problems. The power supplies are designed to operate at a particular voltage and within an acceptable range of voltage fluctuations. AC OK indicators next to the AC inlets on the server back panel are green when the power is connected, and off when it is not connected. The AC OK and DC OK indicators on the PS indicator panels on the front panel are green when the PS is functioning properly.	Verify that both AC power cords are connected to the server. Verify that the correct power is present at the outlets and monitor the power to verify that it is within the acceptable range. You can verify proper connection and operation by verifying the power supply (PS) indicator panels, which are located at the back of the server on the power supplies. Lit green AC OK indicators show a properly functioning power supply. An amber AC OK indicator indicates that the AC power to the power supply is insufficient.	Use the AC power cord Velcro retaining clips and position the cords to minimize the risk of accidental disconnection. Ensure that the AC circuits that supply power to the server are stable and not overburdened.
Power Supplies (PS0-3)	The server power supplies (PS) provide the necessary server voltages from the AC power outlets. If the power supplies are inoperable, unplugged, or disengaged from the internal connectors, the server cannot power on. Note - Use the Velcro straps on the back of the server to secure the power cord connectors to the back of the power supplies. The Velcro retaining straps minimize the risk of accidental disconnection.	Verify that the AC cables are connected to both power supplies. Verify that the power supplies are operational (the PS indicator panel must have a lit green AC OK indicator). Ensure that the power supply is properly installed. A power supply that is not fully engaged with its internal connector does not have power applied and does not have a lit green AC OK indicator.	When a power supply fails, replace it immediately. To ensure redundancy, the server SMOD has two power supplies. This redundant configuration prevents server downtime, or an unexpected shutdown, due to a failed power supply. The redundancy allows the server to continue to operate if one of the power supplies fails. However, when a server SMOD is being powered by a single power supply, the redundancy no longer exists, and the risk for downtime or an unexpected shutdown increases. When installing a power supply, ensure that it is fully seated and engaged with its connector inside the drive bay. A properly installed power supply has a lit green AC OK indicator.