HP ProLiant DL580 Generation 3 User Manual page 61

CAUTION: Failure to completely open the processor locking lever
prevents the processor from seating during installation, leading to
hardware damage.
6. Install the processor assembly into the processor socket.
IMPORTANT: Determine the correct processor orientation by
observing the guide pins on the base of the processor retaining bracket
and the three corresponding guide slots on the processor assembly.
7. Insert the processor assembly into the processor socket, and close the locking
lever.
Hardware options installation 61