Troubleshooting Power Issues
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.
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
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
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.
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
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
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