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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.

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

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

Figure 1. Memory module and processor location
Memory module and processor location
Table 1. Memory module and processor location
1 Memory module slot 9–124 Memory module slot 1–4
2 Processor socket 25 Memory module slot 5–8
3 Processor socket 16 Memory module slot 13–16

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

Table 2. Channel and slot information of DIMMs around a processor
ProcessorProcessor 1Processor 2
Memory module slot number12345678910111213141516

Memory module installation guideline

  • Two types of configurations are supported. Consider corresponding rules and population sequence accordingly:
  • A label on each DIMM identifies the DIMM type. This information is in the format xxxxx nRxxx PC4-xxxxx-xx-xx-xxx. Where n indicates if the DIMM is single-rank (n=1) or dual-rank (n=2).

  • At least one DIMM is required for each processor. Install at least eight DIMMs per processor for good performance.

  • When you replace a DIMM, the server provides automatic DIMM enablement capability without requiring you to use the Setup utility to enable the new DIMM manually.

  • Mixing x4 and x8 DIMMs in the same channel is allowed.

  • Install DIMMs of the same speed for optimal performance. Otherwise, the BIOS will find and run the lowest speed among all channels.