Samsung CLP 550 - Manual (Page 268)

I NSTALLING P RINTER O PTIONS F.10
If you replace the network interface card with a new one,
remove the two screws and the old card.
5 Align the connector on the network interface card with the
connector on the control board. Make sure that the jacks on
the card go through the holes. Push the card firmly into the
connector until it is completely inserted into place.
6 Tighten the two screws.