Dell Inspiron 545s (Early 2009) - Manual (Page 45)

Compare the system board that you just removed with the replacement system board to ensure that they are identical.
Replacing the System Board
1. Gently align the system board into the chassis and slide it towards the back of the computer.
Inspiron 535s/537s
Inspiron 545s/546s
1 screws (8) 2 system board
CAUTION: Ensure that the port retention springs are not damaged while replacing the sytem board.
1 back of the computer 2 port retention spring
1 back of the computer 2 port retention springs (3)