Dell OptiPlex 990 Desktop, Service Manual, Page: 89 / 94

System Board Connectors
Intruder connector one 3-pin connector
Power connector
Mini-Tower, Desktop,
Small Form Factor one 24-pin and one 4-pin connector
Ultra Small Form Factor one 8-pin, one 6-pin, and one 4-pin
connector
Controls and Lights
Front of the computer:
Power button light Blue light — Solid blue light
indicates power-on state; blinking
blue light indicates sleep state of
the computer.
Amber light — Solid amber light
when the computer does not start
indicates a problem with the
system board or power supply.
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. For more
information on the diagnostic 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.
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