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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 the number of processors 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.

Your server has 12 memory slots with 12 channels. For a list of supported memory options, see:

Lenovo ServerProven website.

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 is shown below.

Memory modules and processors layout

Figure 1. Memory modules and processors layout
Memory module and processor location

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
DIMM No.121110987 654321

Memory module installation guideline

  • At least one DIMM is required. Install at least six DIMMs for good performance.

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

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

  • Only one rank and two rank DIMM mixing is allowed in a system.

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

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

General DIMM mixing rules

DIMMsCoexist in a system
9x4 RDIMM and other RDIMM typesx
3DS RDIMM and other DIMM typesx
128 GB 3DS RDIMM and 256 GB 3DS RDIMMx
x4 DIMM and x8 DIMMx
16 Gbit (16 GB/32 GB/64 GB) DIMM and 24 Gbit (48 GB/96 GB) DIMMx
DIMMs with different capacity
Single-rank DIMM and dual-rank DIMM
DIMMs manufactured by different vendors
  • When installing DIMMs with different capacity, install the DIMM with the highest capacity first following the population sequence.

  • For optimal performance, it is recommended to install DIMMs with identical capacity and rank in the same channel of the two processors.

  • 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.

Memory module installation order

The following table shows the DIMM population sequence.

Table 2. DIMM population sequence
2 DIMMs     76     
4 DIMMs9764
6 DIMMs   987654   
8 DIMMs119876542
10 DIMMs 111098765432 
12 DIMMs121110987654321