Dell Precision T3400 (Late 2007) - Manual (Page 247)

Adding and Replacing Parts
247
NOTICE:
To avoid damage, ensure that the processor aligns properly with the
socket, and do not use excessive force when you install the processor.
7 Set the processor lightly in the socket and ensure that the processor is
positioned correctly.
8 When the processor is fully seated in the socket, close the processor cover.
Ensure that the tab on the processor cover is positioned underneath the
center cover latch on the socket.
9 Pivot the socket release lever back toward the socket and snap it into place
to secure the processor.
NOTICE:
If you are not installing a processor upgrade kit from Dell, reuse the
original heat-sink assembly when you replace the processor.
If you installed a processor replacement kit from Dell, return the original
heat-sink assembly and processor to Dell in the same package in which
your replacement kit was sent.
10 Install the heat-sink assembly:
a Place the heat-sink assembly back onto the heat-sink assembly
bracket.
b Rotate the heat-sink assembly down towards the computer base and
tighten the two capture screws.
NOTICE:
Ensure that the heat-sink assembly is correctly seated and secure.
7 front alignment notch 8 socket and processor pin-1
indicator
9 rear alignment notch