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Memory module installation rules and order

Memory modules must be installed in a specific order based on the memory configuration that you implement on your server.

General mixing rules:

DIMMsCoexist in a channelCoexist in a system
RDIMMs and Performance+ RDIMMs  
3DS RDIMMs and other DIMM types  
128 GB 3DS RDIMMs and 256 GB 3DS RDIMMs  
DIMMs of different DRAM density (8Gbit and 16 Gbit)11
DIMMs of different DRAM data width (x4 and x8) 
DIMMs of different rank22
DIMMs manufactured by different vendors
DIMMs of different voltage3  
ECC and Non-ECC DIMMs4  
  1. Install the one with the higher density first.

  2. Install the one with the higher rank first.

  3. Only support 1.2 V.

  4. Only support ECC DIMMs.

DIMM compatibility (based on general mixing rules)
TypeOptionCapacityDRAM data widthDRAM density
RDIMM116 GBx88 Gbit
232 GBx48 Gbit
332 GBx816 Gbit
464 GBx416 Gbit
Performance+ RDIMM532 GBx816 Gbit
664 GBx416 Gbit
3DS RDIMM7128 GBx416 Gbit
8256 GBx416 Gbit

Support mixing within a channel:

  • Options 1 and 3

  • Options 2 and 4

Support mixing within a system:

  • Options 1 to 4 (Install the one with higher DRAM density first.)

  • Options 5 and 6 (Install the one with higher capacity first.)

Alternatively, for balancing memory and for better performance, consider below rules:
  • Balance memory capacity per channel pair on a given CPU.

  • Balance memory capacity per CPU socket when 2 CPUs are installed.

  • In cases of using Performance+ RDIMMs to maximize memory operating speed, ensure that Performance+ RDIMMs with the same capacity are populated on 2DPC. Otherwise, there will be no performance gain.

  • When only one DIMM is to be populated in a given channel, it must be populated in DIMM slot 1 (physically farthest away from the CPU).

  • The server supports single DIMM as a minimum configuration, however, full memory bandwidth requires one DIMM per channel (A–H) be populated. For best performance, populate all 8 channels per socket, with every channel having the same capacity.


Detailed instructions for balancing memory configurations for your server can be found at:

Balanced Memory Configurations with Second-or-Third-Generation AMD EPYC Processors

Recommended population order (based on general rules)

1 CPU installed:

DIMM locations on the system board

2 CPUs installed:

DIMM locations on the system board

There are performance-optimized 6-DIMM and 12-DIMM configurations for server models with one 7003 series CPU and 12-DIMM and 24-DIMM configurations for server models with two 7003 series CPUs. For details, see the table below.
CPU Qty.DIMM Qty.Performance-optimized DIMM population order
161, 3, 7, 10, 14, 16
121, 2, 3, 4, 7, 8, 9, 10, 13, 14, 15, 16
2121, 3, 7, 10, 14, 16, 17, 19, 23, 26, 30, 32
241, 2, 3, 4, 7, 8, 9, 10, 13, 14, 15, 16, 17, 18, 19, 20, 23, 24, 25, 26, 29, 30, 31, 32