IBM System x3550 M4 - System-Board Leds; System-Board Optional-Device Connectors

System-board LEDs
The following illustration shows the light-emitting diodes (LEDs) on the system
board.
System-board optional-device connectors
The following illustration shows the connectors on the system board for the
optional devices.
Figure 18. System-board LEDs
32 IBM System x3550 M4 Type 7914: Installation and Service Guide