Apple Workgroup Server 6150/66 - Manual (Page 44)

3 Remove the cover from the access port on the back panel of your server and set it aside.
Use your thumb to push out the access port cover.
4 Touch the metal part of the power supply case inside the server to discharge static
electricity.
Always do this before you touch any parts, or install any components, inside
the server.
Power supply
Access port cover
28 Chapter 3 / Expanding Your Server and Connecting Other Equipment