Technical rules for memory modules

For a list of supported memory options, 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 for each processor. Install at least six DIMMs per processor for good performance.

• When you replace a DIMM, the server provides automatic DIMM enablement capability without requiring you to use the Setup utility to enable the new DIMM manually.

• All DIMMs must be either all RDIMMs, or DDR4 and PMEMs.

• 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.

• Memory modules from different vendors are supported.

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

  Table 1. DIMM compatibility. Table of DIMM mixing support

  DIMM Types	RDIMM	3DS RDIMM	PMEMs
  RDIMM	V	X	V
  3DS RDIMM	X	V	V
  PMEMs	V	V	X

See the following to locate the DIMM slots and corresponding channels.

Figure 1. Processor and memory module layout