NEC Express 5800/230Eh - Manual (Page 250)

9-44 Upgrading Your Server
5. Raise the lever on the socket.
6. Raise the holder.
7. Put the CPU on the socket slowly and carefully.
IMPORTANT: Make sure of the orientation of CPU. A pin mark is
placed on CPU and CPU socket to prevent an incorrect insertion. Check
the pin marks on CPU and socket before inserting CPU into socket.
Pin mark