Dell Precision 390 - Manual (Page 101)

I/O-Panel Components
Removing the I/O Panel
1. Follow the procedures in Before You Begin .
2. Remove the computer cover (see Removing the Computer Cover ).
3. Loosen the two captive screws on each side of the heat-sink assembly.
4. Rotate the heat-sink assembly upward, and remove it from the computer.
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions in the Product Information Guide.
CAUTION: To guard against electrical shock, always unplug your computer from the electrical outlet before opening the cover.
NOTICE: To prevent static damage to components inside your computer, discharge static electricity from your body before you touch any of your
computer's electronic components. You can do so by touching an unpainted metal surface on the computer.
1 USB port 2 diagnostic, hard-drive access, and network
integrity lights
3 headphone
connector
4 microphone
connector
NOTE: To loosen the two captive screws on each side of the heat-sink assembly, you need a long Phillips screwdriver.
CAUTION: Despite having a plastic shield, the heat-sink assembly may be very hot during normal operation. Ensure that the assembly has had
sufficient time to cool before you touch it.