General DIMM and NVDIMM-N slot population guidelines

Before reviewing the population guidelines, review the "Persistent memory and NVDIMM terminology."

Population requirements

  • Do not mix RDIMMs, UDIMMs, and LRDIMMs.
  • When NVDIMM-Ns are installed on a server, install at least one regular DIMM in a DIMM slot associated with the first processor installed.
  • Install DIMMs only if the corresponding processor is installed.
  • When mixing regular DIMMs and NVDIMM-Ns in a channel, install the regular DIMMs first and then install the NVDIMM-Ns in the channel.
  • When installing NVDIMM-Ns in a server with more than 16 DIMM slots and using the HPE 96W Smart Storage Battery, install a maximum of 16 NVDIMM-Ns in the server.
  • When single-rank, dual-rank, and quad-rank DIMMs are populated for two DIMMs per channel or three DIMMs per channel, install the higher numbered rank DIMM first in the channel (starting from the farthest DIMM slot). For example, install the quad-rank DIMM first, the dual-rank DIMM next, and the single-rank DIMM last.

Population recommendations

  • To utilize all memory channels and provide best performance when one processor is installed, install regular DIMMs in sequential alphabetic order: A, B, C, D, E, F, and so forth.
  • When two processors are installed, install the regular DIMMs in sequential alphabetic order balanced between the two processors: P1-A, P2-A, P1-B, P2-B, P1-C, P2-C, and so forth. If installing NVDIMM-Ns in an unbalanced configuration, see "Balanced and unbalanced NVDIMM configurations."
  • To achieve the best performance, install only two DIMMs per channel in servers with three DIMM slots per channel. When three DIMMs per channel are populated, the speed reduces from 2400 MT/s or 2133 MT/s to 1600 MT/s.

    The operating frequency is reduced to 1867 MT/s if the following are true:

    • If any channel in the system is populated with two DIMMs per channel and at least one of them is NVDIMM.
    • If no channel in the system is configured with three DIMMs per channel.
    • If a channel in the system configured with two DIMMs per channel is populated with all regular DIMMs, an NVDIMM-N installed in a one DIMM per channel configuration runs at 2133 MT/s.

For more information about server memory, see the Hewlett Packard Enterprise website (