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Memory module installation order

Memory modules must be installed in a specific order based on the memory configuration that you implement and the number of processors and memory modules installed in the compute node.


List of supported memory module is different for 1st generation (Skylake) and 2nd generation (Cascade Lake) Intel Xeon processors. Make sure to install compatible memory modules to avoid system error. For a list of supported DIMMs, see: Lenovo ServerProven website.

Memory installation requirements:

  • A label on each DIMM identifies the DIMM type. This information is in the format xxxxx nRxxx PC4-xxxxx-xx-xx-xxx. Where n indicates if the DIMM is single-rank (n=1) or dual-rank (n=2).

  • At least one DIMM is required or each processor. Install at least six DIMMs per processor for good performance.

  • The following table includes all the feasible combinations of different types of DIMMs:

    Table 1. DIMM compatibility
  • When you replace a DIMM, the compute node provides automatic DIMM enablement capability without requiring you to use the Setup utility to enable the new DIMM manually.

  • Mixing x4 and x8 DIMMs in the same channel is allowed.

  • Install DIMMs of the same speed for optimal performance. Otherwise, the BIOS will find and run the lowest speed among all channels.

  • Always populate DIMMs with the maximum number of ranks in the farthest DIMM slot, followed by the nearest DIMM slot.