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Memory module installation rules and order

Memory modules must be installed in a specific order based on the memory configuration of 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. DIMM and processor location
DIMM location
Table 1. DIMM and processor location
1 DIMM connectors 13–184 Processor socket 1
2 Processor socket 25 DIMM connectors 7–12
3 DIMM connectors 1–66 DIMM connectors 19–24
Table 2. Channel and slot information of DIMMs around processor 1 and 2.

The memory-channel configuration table is a three-column table that shows the relationship between the processors, memory controllers, memory channels, slot number and the DIMM connectors.

Integrated Memory Controller (iMC)Controller 0Controller 1
ChannelChannel 2Channel 1Channel 0Channel 0Channel 1Channel 2
Slot010101101010
DIMM connector (processor 1)123456789101112
DIMM connector (processor 2)242322212019181716151413
  • Independent memory mode
    Independent memory mode provides high performance memory capability. The memory channels can be populated with DIMMs in any order in independent mode. You can populate all six channels on each processor in any order with no matching requirements. Individual channels can run at different DIMM timings, but all channels must run at the same interface frequency.
  • Memory mirroring mode
    In mirrored-channel mode, mirroring of the memory is done between Channels 0, 1, and 2 or Channels 3, 4, and 5. One channel is used as a backup of the other, which provides redundancy. The memory contents on channel 0 are duplicated in channel 1, and the memory contents of channel 2 are duplicated in channel 3. The effective memory that is available to the system is only half of what is installed.
  • Memory rank sparing mode
    In rank-sparing mode, one memory DIMM rank serves as a spare of the other ranks on the same channel. The spare rank is held in reserve and is not used as active memory. The spare rank must have identical or larger memory capacity than all the other active DIMM ranks on the same channel. After an error threshold is surpassed, the contents of that rank is copied to the spare rank. The failed rank of DIMMs is taken offline, and the spare rank is put online and used as active memory in place of the failed rank.
  • DC Persistent Memory Module - Memory Mode
    Memory modules must be installed in a specific order based on the memory configuration that you implement on your node. Below is the information of Memory Mode.