Dell Precision 390 - Manual (Page 26)

Back View (Tower Orientation)
plastic handle behind the badge.
9 power button Press to turn on the computer.
NOTICE: To avoid losing data, do not use the power button to turn off
the computer. Instead, perform an operating system shutdown.
NOTE: The power button can also be used to wake the system or to
place it into a power-saving state. See Power Management for more
information.
10 power light The power light illuminates and blinks or remains solid to indicate
different states:
¡ No light — The computer is turned off.
¡ Steady green — The computer is in a normal operating
state.
¡ Blinking green — The computer is in a power-saving state.
¡ Blinking or solid amber — See Power Problems .
To exit from a power-saving state, press the power button or use the
keyboard or the mouse if it is configured as a wake device in the
Windows Device Manager. For more information about sleep states and
exiting from a power-saving state, see
Power Management .
See Diagnostic Lights for a description of light codes that can help you
troubleshoot problems with your computer.
11 microphone
connector
Use the microphone connector to attach a personal computer
microphone for voice or musical input into a sound or telephony
program.
12 headphone
connector
Use the headphone connector to attach headphones.
13 diagnostic
lights (4)
Use these lights to help you troubleshoot a computer problem based
on the diagnostic code. For more information, see
Diagnostic Lights .
14 network link
light
The network link light is on when a good connection exists between a
10-Mbps, 100-Mbps, or 1000-Mbps (1-Gbps) network and the computer.
1 power
connector
Insert the power cable.
2 voltage
selection
switch
See the safety instructions in the Product Information Guide for more
information.
3 back panel
connectors
Plug serial, USB, and other devices into the appropriate connector.
4 card slots Access connectors for any installed PCI or PCI Express cards.
NOTE: The upper five connector slots support full-length cards; the
connector slot at the bottom supports a half-length card.