Dell OptiPlex 790 (Early 2011) - Manual (Page 97)

Controls and Lights
Blinking amber light indicates a problem
with the system board.
Drive activity light Blue light — Blinking blue light indicates
that the computer is reading data from or
writing data to the hard drive.
Diagnostic lights Four lights located on the front panel of the
computer.
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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