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Independent mode

In independent memory mode, memory channels can be populated with DIMMs in any order and you can populate all channels for each processor in any order with no matching requirements. Independent memory mode provides the highest level of memory performance, but lacks failover protection. The DIMM installation order for independent memory mode varies based on the number of processors and memory modules installed in the server.

Follow the rules below when installing memory modules in independent mode:
  • All memory modules to be installed must be of the same type.

  • Memory modules from different vendors are supported.

  • There must be at least one DDR4 DIMM per socket.

  • In each memory channel, populate slot 0 first.

  • If a memory channel has two DIMMs, populate the DIMM with a higher number of ranks in slot 0; if the two DIMMs have the same number of ranks, populate the DIMM with a higher capacity in slot 0.

  • A maximum of 8 logical ranks (ranks seen by the host) per channel is allowed.

  • A maximum of two different DIMM capacities are supported per system.
    • For channels A, C, E, and G, populated DIMMs must have the same total capacity for each channel.

    • For channels B, D, F, and H, populated DIMMs must have the same total capacity for each channel, which can be different from that of the other set (channels A, C, E, and G).

  • If there are more than two DIMMs, populate them in a right-and-left symmetrical manner across a CPU socket.

The following table shows the sequence of populating memory modules (with the same capacity) for independent mode when only one processor (CPU 1) is installed.

Table 1. Independent mode with one processor (DIMMs with the same capacity)
ConfigurationDIMM slots
 
12345678910111213141516
1 DIMM3
2 DIMMs  3   7         
4 DIMMs1371014
6 DIMMs1 3   7  10   14 16
8 DIMMs1,2135710121416
12 DIMMs1234  78910  13141516
16 DIMMs1,212345678910111213141516
Note
  1. DIMM configurations that support Sub NUMA Clustering (SNC), which can be enabled via UEFI. SNC is not supported if DIMM population does not follow the sequence indicated by the table above.

  2. DIMM configurations that support Software Guard Extensions (SGX). See Enable Software Guard Extensions (SGX) to enable this feature.

The following table shows the sequence of populating memory modules (with different capacities) for independent mode when only one processor (CPU 1) is installed.

Table 2. Independent mode with one processor (DIMMs with different capacities)
ConfigurationDIMM slots
 
12345678910111213141516
2 DIMMs35
4 DIMMs  3 5      12 14  
8 DIMMs1,2135710121416
12 DIMMs1,21 345 78910 121314 16
16 DIMMs1,212345678910111213141516
Note
  1. DIMM configurations that support Sub NUMA Clustering (SNC), which can be enabled via UEFI. SNC is not supported if DIMM population does not follow the sequence indicated by the table above.

  2. DIMM configurations that support Software Guard Extensions (SGX). See Enable Software Guard Extensions (SGX) to enable this feature.

The following table shows the sequence of populating memory modules (with the same capacity) for independent mode when two processors (CPU 1 and CPU 2) are installed.

Table 3. Independent mode with two processors (DIMMs with the same capacity)
ConfigurationDIMM slots
12345678910111213141516
2 DIMMs3
4 DIMMs  3   7         
8 DIMMs1371014
12 DIMMs1 3   7  10   14 16
16 DIMMs1,2135710121416
24 DIMMs1234  78910  13141516
32 DIMMs1,212345678910111213141516
ConfigurationDIMM slots
17181920212223242526272829303132
2 DIMMs19
4 DIMMs  19   23         
8 DIMMs119232630
12 DIMMs17 19   23  26   30 32
16 DIMMs1,21719212326283032
24 DIMMs17181920  23242526  29303132
32 DIMMs1,217181920212223242526272829303132
Note
  1. DIMM configurations that support Sub NUMA Clustering (SNC), which can be enabled via UEFI. SNC is not supported if DIMM population does not follow the sequence indicated by the table above.

  2. DIMM configurations that support Software Guard Extensions (SGX). See Enable Software Guard Extensions (SGX) to enable this feature.

The following table shows the sequence of populating memory modules (with different capacities) for independent mode when two processors (CPU 1 and CPU 2) are installed.

Table 4. Independent mode with two processors (DIMMs with different capacities)
ConfigurationDIMM slots
12345678910111213141516
4 DIMMs35
8 DIMMs  3 5      12 14  
16 DIMMs1,2135710121416
24 DIMMs1,21 345 78910 121314 16
32 DIMMs1,212345678910111213141516
ConfigurationDIMM slots
17181920212223242526272829303132
4 DIMMs1921
8 DIMMs  19 21      28 30  
16 DIMMs1,21719212326283032
24 DIMMs1,217 192021 23242526 282930 32
32 DIMMs1,217181920212223242526272829303132
Note
  1. DIMM configurations that support Sub NUMA Clustering (SNC), which can be enabled via UEFI. SNC is not supported if DIMM population does not follow the sequence indicated by the table above.

  2. DIMM configurations that support Software Guard Extensions (SGX). See Enable Software Guard Extensions (SGX) to enable this feature.