Dell Precision T3400 (Late 2007) - Manual (Page 170)

170
Adding and Replacing Parts
4 Press the release tab on the card retention cover and pivot the cover open.
NOTE:
You can remove the card retention cover, if desired, and set it aside.
5 Remove the filler bracket to create a card-slot opening, if necessary.
6 Prepare the card for installation.
See the documentation that came with the card for information on
configuring the card, making internal connections, or otherwise
customizing it for your computer.
CAUTION:
Some network adapters automatically start the computer when they
are connected to a network. To guard against electrical shock, be sure to unplug
your computer from its electrical outlet before installing any cards.
NOTE:
The standard length for a PCI card in the last PCI slot (Slot6) is 5.5 in;
however, you can install a 3/4-length PCI card (up to 10.5 in) by removing the second
hard drive bay bracket.
1 release tab 2 card retention cover
3 card retention door
3 1 2