For DIMM socket population rules, see DIMM Population Rules.
The notch ensures that the DIMM is oriented correctly.
If the DIMM does not easily seat into the connector socket, verify that the notch in the DIMM is aligned with the connector key in the connector socket. If the notch is not aligned, damage to the DIMM might occur.
Verify that the power supply AC OK LED is lit.
DDR4 DIMM faults are automatically cleared after a new DIMM has been installed. If you need to manually clear DDR4 DIMM faults, refer to the Oracle Integrated Lights Out Manager (ILOM) 3.2 Documentation Library at http://www.oracle.com/goto/ilom/docs.