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DDR5 DIMMs only

This section contains information about how to install DDR5 registered DIMMs (RDIMMs) and Multiplexed Rank DIMMs (MRDIMMs) properly in configurations without CXL memory modules (CMMs).

Note
MRDIMMs are supported only on servers equipped with processor 6747P, 6761P, 6767P, 6781P, or 6787P.

For DDR5 RDIMMs and MRDIMMs, the following two memory modes are available.

  • Independent mode installation order
    In independent mode, memory channels can be populated with DIMMs in any order, and you can populate all channels for each processor in any order with no matching requirements. Independent mode provides the highest level of memory performance, but lacks failover protection. The DIMM installation order for independent mode varies based on the number of processors and memory modules installed in the server.
  • Mirroring mode installation order
    Mirroring mode provides full memory redundancy while reducing the total system memory capacity in half. Memory channels are grouped in pairs with each channel receiving the same data. If a failure occurs, the memory controller switches from the DIMMs on the primary channel to the DIMMs on the backup channel. The DIMM installation order for memory mirroring varies based on the number of processors and DIMMs installed in the server.