NEC Express5800 series User Manual page 168

Raise the locking lever on the socket.
6.
IMPORTANT:
approx. 120 degrees.
7. Aligning the pins of the CPU with the socket, insert the CPU slowly and gently into the
socket.
IMPORTANT:
Be aware of CPU direction. Pin layouts on two corners among four
differ from others to prevent an incorrect insertion. Confirm the pin
mark and pin layout on the socket, and insert the CPU correctly.
The motherboard has "zero insertion force" sockets. If CPU does
not drop easily into socket holes, make sure lever is in the full-open
position.
Pin mark
158 Upgrading Your NEC Storage
Open the lever until it stops. The bar can be opened to
Retention