See Remove a CMOD.
To remove the CMOD top cover, push the release button, slide the CMOD cover toward the back of the CMOD, and lift it away.
Faulty DIMMs are identified with a corresponding amber LED on the motherboard.
If the DIMM Fault LED is off, then the DIMM is operating properly.
If the DIMM Fault LED is on (amber), then the DIMM is faulty and should be replaced .
To locate the failed DIMM, press and hold the Fault Remind button .
This procedure uses the DIMM fault remind test circuit in the CMOD to identify the failed DIMM. The circuit is a charged, time-limited circuit. Once power is removed from the server you have 10 minutes to use the circuit for troubleshooting.
The Charge Status indicator  lights if the Fault Remind circuit is operational.
The Fault Remind circuit remains charged for about 10 minutes after power is removed from the CMOD, either by disconnecting power from the server, or by removing the CMOD from the chassis. When you press the Fault Remind button, the Charge Status indicator lights if there is enough power to use the fault remind circuit. Otherwise it remains unlit.
Each DIMM slot has a fault indicator. Twelve DIMM fault LED indicators are located next to the DIMM slots.
The DIMM is partially ejected from the socket. This action extracts the DIMM from its connector.
Carefully lift the DIMM straight up to remove it from the socket.
For DIMM replacement instructions, see Install a DIMM.