Nvdimm-N Memory Module Installation Guidelines - Dell EMC PowerEdge R940 Installation And Service Manual

The system supports Flexible Memory Configuration, enabling the system to be configured and run in any valid chipset
architectural configuration. The following are the recommended guidelines for installing memory modules:
● All DIMMs must be DDR4.
● RDIMMs and LRDIMMs must not be mixed.
● NVDIMMs and LRDIMMs must not be mixed.
● NVDIMMs and RDIMMs can be mixed.
● 64 GB LRDIMMs that are DDP (Dual Die Package) LRDIMMs must not be mixed with 128 GB LRDIMMs that are TSV
(Through Silicon Via/3DS) LRDIMMs.
● x4 and x8 DRAM based memory modules can be mixed.
● Up to two RDIMMs can be populated per channel regardless of rank count.
● Up to two LRDIMMs can be populated per channel regardless of rank count.
● A maximum of two different ranked DIMMs can be populated in a channel regardless of rank count.
● If memory modules with different speeds are installed, they will operate at the speed of the slowest installed memory
module(s).
● Populate memory module sockets only if a processor is installed.
○ For single-processor systems, sockets A1 to A12 are available.
○ For dual-processor systems, sockets A1 to A12 and sockets B1 to B12 are available.
● Populate all the sockets with white release tabs first, followed by the black release tabs.
● When mixing memory modules with different capacities, populate the sockets with memory modules with the highest
capacity first.
NOTE: For example, if you want to mix 8 GB and 16 GB memory modules, populate 16 GB memory modules in the
sockets with white release tabs and 8 GB memory modules in the sockets with black release tabs.
● Memory modules of different capacities can be mixed provided other memory population rules are followed.
NOTE: For example, 8 GB and 16 GB memory modules can be mixed.
● In a dual-processor configuration, the memory configuration for each processor must be identical.
NOTE: For example, if you populate socket A1 for processor 1, then populate socket B1 for processor 2, and so on.
● Mixing of more than two memory module capacities in one system is not supported.
● Unbalanced memory configurations will result in a performance loss so always populate memory channels identically with
identical DIMMs for best performance.
● Populate six identical memory modules per processor (one DIMM per channel) at a time to maximize performance.
DIMM population update for Performance Optimized mode with quantity of 4 and 8 DIMMs per processor.
● When the DIMM quantity is 4 per processor, the population is slot 1, 2, 4, 5.
● When the DIMM quantity is 8 per processor, the population is slot 1, 2, 4, 5, 7, 8, 10, 11.

NVDIMM-N memory module installation guidelines

The following are the recommended guidelines for installing NVDIMM-N memory modules:
● Each system supports memory configurations with 1, 2, 4, 6, or 12 NVDIMM-Ns.
● Supported configurations have dual processors and a minimum of 12x RDIMMs.
● Maximum of 12 NVDIMM-Ns can be installed in a system.
● NVDIMM-Ns or RDIMMs must not be mixed with LRDIMMs.
● DDR4 NVDIMM-Ns must be populated only on the black release tabs on processor 1 and 2.
● For systems with four processors, RDIMMs populated on processor 3 and 4 must be identical to the number of RDIMMs
populated on processor 1 and 2.
● All slots on configurations 3, 6, 9, and 12 can be used, but a maximum of 12 NVDIMM-Ns can be installed in a system.
NOTE: NVDIMM-N memory slots are not hot-pluggable.
For more information about the supported NVDIMM-N configurations, see the NVDIMM-N User Guide at
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