Dell Precision T7400 (Late 2007) - Manual (Page 207)

Adding and Replacing Parts 207
NOTICE: To connect a network cable, first plug the cable into the network device
and then plug the cable into the computer.
14 Replace the computer cover (see "Replacing the Computer Cover" on
page 145), reconnect the computer and devices to electrical outlets, and
then turn them on.
15 Uninstall the driver for the removed card. See the documentation that
came with the card.
16 If you removed a sound card:
a Enter system setup, select Integrated Audio, and then change the
setting to On.
b Connect external audio devices to the audio connectors on the back
panel of the computer.
17 If you removed a network adapter card:
1 card retention device 2 tab
1
2