Dell Precision T7400 (Late 2007) - Manual (Page 200)

200 Adding and Replacing Parts
12 Rotate the card retainer until it snaps into place.
NOTICE: Do not route card cables behind the cards. Cables routed behind the
cards could cause damage to the equipment.
13 Connect any cables that should be attached to the card.
See the documentation for the card for information about the card’s cable
connections.
14 Press the card retention device back into its original position; push it down
until it clicks into place.
1 release tab 2 card retainer
1
2