IBM System x3550 M4 Installation And Service Manual page 283

Figure 162. Network adapter installation
8. Press the adapter firmly until the pin, and retention brackets engage the
adapter. Make sure the adapter is securely seated on the connector on the
system board.
Attention: Make sure the port connectors on the adapter are aligned
properly with the chassis on the rear of the server. An incorrectly seated
adapter might cause damage to the system board or the adapter.
9. Fasten the thumbscrew on the rear side of the chassis.
Figure 163. Screws engagement
Chapter 6. Removing and replacing components
265