General Memory Module Installation Guidelines - Dell EMC PowerEdge R7515 Installation And Service Manual

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Table 39. Supported memory matrix (continued)
DIMM
Rank
type
RDIMM
1R
2R
LRDIMM
8R

General memory module installation guidelines

To ensure optimal performance of your system, observe the following general guidelines when configuring your system memory. If your
system's memory configurations fail to observe these guidelines, your system might not boot, stop responding during memory
configuration, or operate with reduced memory. This section provides information on the memory population rules and about the non-
uniform memory access (NUMA) for single or dual processor system.
The memory bus may operate at speeds of 3200 MT/s, 2933 MT/s, or 2666 MT/s depending on the following factors:
System profile selected (for example, Performance Optimized, or Custom [can be run at high speed or lower])
Maximum supported DIMM speed of the processors
Maximum supported speed of the DIMMs
NOTE:
MT/s indicates DIMM speed in MegaTransfers per second.
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.
Mixing of memory module capacities in a system is not supported.
If memory modules with different speeds are installed, they 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 A16 are available.
○ In Optimizer Mode, the DRAM controllers operate independently in the 64-bit mode and provide optimized memory performance.
Table 40. Memory population rules
Processor
Single processor
Populate all the sockets with white release tabs first, followed by the black release tabs.
Unbalanced or odd memory configuration results in a performance loss and system may not identify the memory modules being
installed, so always populate memory channels identically with equal DIMMs for best performance.
Minimum recommended configuration is to populate four equal memory modules per processor. AMD recommends limiting processors
in that system to 32 cores or less.
Populate eight equal memory modules per processor (one DIMM per channel) at a time to maximize performance.
NOTE:
Equal memory modules refer to DIMMs with identical electrical specification and capacity that may be from
different vendors.
Memory interleaving with Non-uniform memory access (NUMA)
Non-uniform memory access (NUMA) is a memory design used in multi-processing, where the memory access time depends on the
memory location relative to the processor. In NUMA, a processor can access its own local memory faster than the non-local memory.
NUMA nodes per socket (NPS) is a new feature added that allows you to configure the memory NUMA domains per socket. The
configuration can consist of one whole domain (NPS1), two domains (NPS2), or four domains (NPS4). In the case of a two-socket
platform, an additional NPS profile is available to have whole system memory to be mapped as single NUMA domain (NPS0). For more
information on the memory interleaving for NPSx, see the Memory interleaving population rules section in this topic.
BIOS implementation for NPSx
Capacity
8 GB
16 GB, 32 GB, 64 GB
128 GB
Configuration
Optimizer (Independent channel)
population order
DIMM rated voltage and
speed
DDR4 (1.2V), 3200 MT/s
DDR4 (1.2V), 3200 MT/s
DDR4 (1.2V), 2666 MT/s
Memory population
A{1}, A{2}, A{3}, A{4}, A{5}, A{6},
A{7}, A{8}, A{9}, A{10}, A{11}, A{12},
A{13}, A{14}, A{15}, A{16}
Installing and removing system components
Operating Speed
3200 MT/s
2933 MT/s
3200 MT/s
2933 MT/s
2666 MT/s
2666 MT/s
Memory
population
information
Odd amount of
DIMMs per
processor allowed.
75

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