Dell OptiPlex 990 (Early 2011) - Manual (Page 94)

Controls and Lights
see the Service Manual at
support.dell.com/manuals.
Back of the computer:
Link integrity light on integrated
network adapter Green — a good 10 Mbps
connection exists between the
network and the computer.
Orange — a good 100 Mbps
connection exists between the
network and the computer.
Yellow — a good 1000 Mbps
connection exists between the
network and the computer.
Off (no light) — the computer is not
detecting a physical connection to
the network.
Network activity light on integrated
network adapter Yellow light — A blinking yellow
light indicates that network activity
is present.
Power supply diagnostic light Green light — The power supply is
turned on and is functional. The
power cable must be connected to
the power connector (at the back
of the computer) and the electrical
outlet.
NOTE: You can test the health
of the power system by
pressing the test button. When
the system power supply
voltage is within specification,
the self-test LED lights up. If the
LED does not light up, the
power supply may be defective.
AC power must be connected
during this test.
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