Start with the exact DIMM identifier
A manufacturer part number from an installed module is the most direct starting point. If you do not have one, provide the server make and model, processor generation, required total capacity, and current memory configuration. Note the number of modules already installed and the desired final population, since systems may impose rules about slot order and balanced configurations.
Identify generation and module type
State the DDR generation, such as DDR3 or DDR4, and whether the system requires ECC Registered DIMMs (RDIMMs) or Load-Reduced DIMMs (LRDIMMs). These module types are generally not interchangeable, and a server may support only specific capacities, ranks, or speeds. Include speed and rank when specified by the platform documentation or existing module label.
Avoid mixing incompatible specifications
Modules that share capacity can still differ in rank, organization, voltage, speed, or supported configuration. Provide the complete part number from the module label in the inquiry, and flag whether modules must match an existing population. For a mixed requirement, separate each type into its own line with part number and quantity.