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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 and memory modules installed in the server.

Supported memory types

For information on the types of memory module supported by this server, see Memory section in Technical Specifications.

Information about optimizing memory performance and configuring memory is available at the Lenovo Press website:

Memory - Lenovo Press

In addition, you can take advantage of a memory configurator, which is available at the following site:

Lenovo Enterprise Solutions Configurator (Memory Configurations)

Specific information about the required installation order of memory modules in your server based on the system configuration and memory mode that you are implementing is shown below.

Your server has 12 channels, 12 memory slots, and supports:
  • Capacity:
    • Minimum: 16 GB (1 x 16 GB RDIMM)
    • Maximum: 3 TB (12 x 256 GB 3DS RDIMMs)
  • Type (depending on the model):
    • TruDDR5 4800MHz RDIMM: 16 GB (1Rx8), 32 GB (2Rx8), 48 GB (2Rx8), 96 GB (2Rx4)

    • TruDDR5 4800MHz 10x4 RDIMM: 32 GB (1Rx4), 64 GB (2Rx4)

    • TruDDR5 4800MHz 9x4 RDIMM: 32 GB (1Rx4), 64 GB (2Rx4)

    • TruDDR5 4800MHz 3DS RDIMM: 128 GB (4Rx4), 256 GB (8Rx4)

For a list of supported memory options, see Lenovo ServerProven website.

The following illustration helps you to locate the memory module slots on the system board (system board assembly).
Figure 1. Memory modules and processors layout
Memory module slots on the system board (system board assembly)

The memory-channel configuration table below shows the relationship between the processors, memory controllers, memory channels, and memory module slot numbers.

Table 1. Memory slot and channel identification
UMC No.21504391061178
DIMM No.121110987654321

Memory module installation guideline

Follow the rules below when installing DIMMs:

  • Mixing DIMMs from different vendors is supported in a system.

  • Mixing x4 and x8 DIMMs is not allowed in a system.

  • Mixing 3DS RDIMM and non-3DS RDIMM is not allowed in a system.

  • Mixing 4-rank 3DS RDIMM and 8-rank 3DS RDIMM is not allowed in a system.

  • Mixing EC4 and EC8 DIMMs is not allowed in a system.

  • Mixing 16 Gbit DIMMs (16GB, 32GB and 64GB) and 24 Gbit DIMMs (24GB, 48GB and 96GB) is not allowed in a system.

  • Before installing 24 Gb DRAM RDIMMs, make sure to apply the UEFI firmware version KAE108C or later to the server first and remove all existing 16 Gb DRAM RDIMMs.

  • Only single-rank and dual-rank DIMM mixing is allowed in a system.

  • When installing DIMMs with different capacity, install the DIMM with the highest capacity first following population sequence.

  • For best performance, the population recommends identical memory capacity and rank across all 12 channels.

  • Mixing 128 GB 3DS RDIMM and 256 GB 3DS RDIMM is not allowed in a system.

Memory module installation order

In the following tables:
  • S1-S12 indicate DIMM slots 1-12.

  • 1-12 indicate the installation order.

The following table shows the DIMM population sequence.

Table 2. DIMM population sequence
Total DIMMsSlot number
2 DIMMs     12     
4 DIMMs3124
6 DIMMs   351264   
8 DIMMs73512648
10 DIMMs 79351264108 
12 DIMMs117935126410812