Dell Precision T7400 (Late 2007) - Manual (Page 184)

184 Adding and Replacing Parts
NOTE: Align the memory module carefully to ensure that it is facing the correct
direction; FBDs on memory riser cards 1 and 2 face a different direction than those
on riser cards 3 and 4.
9 Align the notch on the bottom of the module with the crossbar in the
connector.
NOTICE: To avoid damage to the memory module, press the module straight down
into the connector while you apply equal force to each end of the module.
10 Insert the module into the connector until the module snaps into position.
If you insert the module correctly, the securing clips snap into the cutouts
at each end of the module.
1 cutouts (2) 2 memory module
3 notch 4 crossbar
3
2
1
4