Figure 4. DRAM and Intel Optane PMem population rules
We recommend the following best practices for populating PMem modules:
- As shown in the figure above, if a PMem module and a DDR4 DIMM are populated on the same memory channel, always populate the PMem module in Slot 1 (black tab).
- Always populate PMem modules across the integrated Memory Controllers (iMC) and across CPU sockets first before populating them within a single iMC or within a single CPU socket. Using the above figure as an example, we recommend that you populate CH 4 Slot 1 before populating CH 2 Slot 1 within the same CPU socket. This maximizes the efficient use of the memory channels.
- If the PMem is configured in Memory Mode, the recommended DRAM to PMem capacity ratio is 1:4 to 1:16 per iMC.
- We recommend a balanced configuration in which each memory channel is populated with a DDR4 DIMM and a PMem module. We recommend that you populate all channels with lesser capacity PMem modules, instead of populating fewer channels with higher capacity PMem modules. For example, we recommend that you populate 6 x 128 GB PMem modules (768 GB) per CPU socket as opposed to 4 x 256 GB PMem modules (1 TB), as shown in the figure above.
For further details on PMem support, best practices, and latest updates with PowerEdge servers, see the Dell EMC Intel Optane PMem User's Guide.