Dell 400 Owner's Manual page 88

4 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.
release tab
*"piano" bracket
5 If your computer includes a card retention mechanism, to remove the x16 card:
Pivot the mechanism upward and gently squeeze in on the sides to release the
a
mechanism from the two tab slots holding it in place.
Set the retention mechanism aside in a secure location.
b
NOTE:
For full-length PCI-E cards, if a "piano" bracket is present on your computer you need to rotate it
upward by pressing the tabs on the side of the bracket toward each other.
PCI Express
x16 card
PCI Express x16
card slot
88
Removing and Installing Parts
card retention mechanism
*may not be present on all computers
securing tab
card retention
door
PCI Express x1
card
PCI Express x1
card slot