IBM System i Manual page 154

Attaching devices by using a system port
Notes:
1. For the IBM System p5 or eServer p5 servers, any other application that uses a system port requires a system port
adapter to be installed into a PCI slot.
2. The attachment of high availability cluster multiprocessing IBM (HACMP) cables to a system port on the back of
the server is not supported.
Connecting the power cords
__ You should route the power cords through the retention rings or under the retention brackets that are provided
to prevent the power cords from becoming unplugged unexpectedly.
__ If your server is equipped with a retention ring, route the power cord through the ring before you plug it
into the back of the server, as shown here:
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System i and System p: Cabling your server