Dell Precision T5400 (Late 2007) - Manual (Page 284)

284 Adding and Replacing Parts
15 Remove any components that restrict access to the system board.
16 Disconnect all cables from the system board.
17 Before you remove the existing system board, visually compare the
replacement system board to the existing system board to make sure that
you have the correct part.
18 Remove the nine system board screws.
19 Lift the system board from the computer.
20 Place the system board that you just removed next to the replacement
system board.
Replacing the System Board
1 Transfer components from the existing system board to the replacement
system board:
a Remove the memory modules and install them on the replacement
board (see "Memory" on page 187 for more information).
1 screws (9) 2 system board
1 2