Dell Dimension 9100 Owner's Manual page 74

Installing a PCI Express Card
1 Follow the procedures in "Before You Begin" on page 55.
release tabs (2)
card retention
door
2 If present on your computer, rotate the lever on the chassis wall upward.
3 Push the two release tabs on the card retention door toward each other and pivot the door
open. Because the door is captive, it will remain in the open position.
74
Removing and Installing Parts
alignment bar
alignment guide
filler bracket
*lever on chassis wall
*may not be present on all computers