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Installing a DIMM

Use this information to install a DIMM.

Before you install a DIMM, complete the following steps:
  1. Read Safety and Installation guidelines.
  2. Read the documentation that comes with the DIMMs.
  3. If the compute node is installed in a chassis, remove it (see Removing a compute node from a chassis for instructions).
  4. Carefully lay the compute node on a flat, static-protective surface, orienting the compute node with the bezel pointing toward you.

This component can be installed as an optional device or as a CRU. The installation procedure is the same for the optional device and the CRU.

After you install or remove a DIMM, you must change and save the new configuration information by using the Setup utility. When you turn on the compute node, a message indicates that the memory configuration has changed. Start the Setup utility and select Save Settings (see Using the Setup utility for more information) to save changes.

If you are installing a DIMM as a result of a DIMM failure, you might have to reenable the DIMM. To re-enable the DIMM, complete the following steps:
  1. Verify that the amount of installed memory is the expected amount of memory through the operating system, by watching the monitor as the compute node starts, by using the CMM sol command, or through Flex System Manager management software (if installed).
  2. Run the Setup utility to reenable the DIMMs (see Using the Setup utility for more information).

The compute node has a total of 24 dual inline memory module (DIMM) connectors. The compute node supports low-profile (LP) DDR4 DIMMs with error-correcting code (ECC) in 4 GB, 8 GB, 16 GB, 32 GB and 64 GB capacity.

The following illustration shows the system-board components, including DIMM connectors.


Graphic illustrating the system-board connectors

The memory is accessed internally through four channels. Each memory channel has three DIMM connectors for each microprocessor (six total). Each channel can have a maximum of eight ranks. The following table lists the memory channels and shows which DIMM connectors are in the channel for each microprocessor.

Table 1. Memory-channel configuration.

The memory-channel configuration table is a three-column table that shows the relationship between microprocessors, memory channels, and the DIMM connectors. Column 1 lists microprocessors one and two. Column 2 identifies the memory channels that are associated with each microprocessor. Column 3 lists the DIMM connectors that are in each memory channel.

MicroprocessorMemory channelDIMM connectors
Microprocessor 1Channel A4, 5, and 6
Channel B1, 2, and 3
Channel C7, 8, and 9
Channel D10, 11, and 12
Microprocessor 2Channel A19, 20, and 21
Channel B22, 23, and 24
Channel C16, 17, and 18
Channel D13, 14, and 15

Depending on the memory mode that is set in the Setup utility, the compute node can support a minimum of 4 GB and a maximum of 768 GB of system memory in a compute node with one microprocessor. If two microprocessors are installed, the compute node can support a minimum of 8 GB and a maximum of 1536 GB of system memory.

Depending on the memory mode that is set in the Setup utility, the compute node can support a minimum of 4 GB and a maximum of 384 GB of system memory in a compute node with one microprocessor. If two microprocessors are installed, the compute node can support a minimum of 8 GB and a maximum of 768 GB of system memory.

The following notes describe information that you must consider when you install memory:

  • Use only registered (RDIMM) DDR4 DIMMs.
  • Maximum DIMM capacity:
    • Registered DIMMs (RDIMMs): 768 GB (using 32 GB RDIMMs)
    • Load Reduced DIMMs (LRDIMMs): 1536 GB (using 64 GB LRDIMMs)
  • RDIMM sizes supported (GB): 4, 8, 16, 32
  • LRDIMM sizes supported (GB): 32, 64
  • You cannot mix RDIMMs and LRDIMMs in the same compute node.
  • DIMMs are verified as authentic Lenovo modules by the UEFI software. If any non-authentic DIMMs are detected, an informational message appears in the system event log and memory performance might be limited. Non-authentic DIMMs are not covered by your Lenovo warranty.
  • Install DIMMs in sets of four to optimize performance.
  • Installing an equal amount of memory for each microprocessor is recommended.
  • If DIMMs of different speeds are installed, memory on a channel operates at the speed of the lowest-speed DIMM in the channel.
  • A total of eight ranks on each channel is supported.
  • If multi-rank DIMMs are installed, install higher ranking DIMMS first starting in the connector at the end of the memory channel.
  • Quad-rank RDIMMs are not supported.
  • Rank multiplication is supported allowing up to three DIMMs per channel.
  • If you install LRDIMMs in a 3 DIMM per channel configuration, performance might be reduced compared to standard DIMMs.
  • Mixing of mirrored and non-mirrored modes is not supported.
  • Lock-step channel mode is not supported.

The compute node supports the following DIMM speeds based on the number of DIMMs installed per channel:

Table 2. DIMM per channel speeds.

The supported DDR4 DIMM table is a three-column table where the rows indicate characteristics for the supported DIMMs. Column 1 describes the DIMM. Column 2 lists the number of DIMMs installed per channel. Column 3 lists the DIMM speed frequency.

Memory DescriptionDIMMs per channelSpeed (MHz)
4 GB (1Rx8, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM12133 MHz
4 GB (1Rx8, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM22133 MHz
4 GB (1Rx8, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM31600 MHz
8 GB (1Rx8, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM12133 MHz
8 GB (1Rx8, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM22133 MHz
8 GB (1Rx8, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM31600 MHz
8 GB (2Rx8, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM12133 MHz
8 GB (2Rx8, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM22133 MHz
8 GB (2Rx8, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM31600 MHz
16 GB (2Rx4, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM12133 MHz
16 GB (2Rx4, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM22133 MHz
16 GB (2Rx4, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM31866 MHz
32 GB (2Rx4, 8 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM12133 MHz
32 GB (2Rx4, 8 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM22133 MHz
32 GB (2Rx4, 8 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz RDIMM31600 MHz / 1866 MHz
32 GB (2Rx4, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz LRDIMM12133 MHz
32 GB (2Rx4, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz LRDIMM22133 MHz
32 GB (2Rx4, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz LRDIMM31866 MHz
64 GB (2Rx4, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz LRDIMM12133 MHz
64 GB (2Rx4, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz LRDIMM22133 MHz
64 GB (2Rx4, 4 Gbit, 1.2V) PC4-17000 TruDDR4 2133 MHz LRDIMM31600 MHz / 1866 MHz
Table 3. DIMM per channel speeds.

The supported DDR4 DIMM table is a three-column table where the rows indicate characteristics for the supported DIMMs. Column 1 describes the DIMM. Column 2 lists the number of DIMMs installed per channel. Column 3 lists the DIMM speed frequency.

Memory DescriptionDIMMs per channelSpeed (MHz)
8 GB (1Rx4, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM12400 MHz
8 GB (1Rx4, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM22400 MHz
8 GB (1Rx4, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM31866 MHz
8 GB (2Rx8, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM12400 MHz
8 GB (2Rx8, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM22133 MHz
8 GB (2Rx8, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM31866 MHz
16 GB (2Rx4, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM12400 MHz
16 GB (2Rx4, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM22400 MHz
16 GB (2Rx4, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM31866 MHz
32 GB (2Rx4, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM12400 MHz
32 GB (2Rx4, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM22400 MHz
32 GB (2Rx4, 4 Gbit, 1.2V) PC4-19200 DDR4 2400 MHz LP RDIMM31866 MHz
There are three memory modes:
  • Independent-channel mode: Independent-channel mode provides a maximum of 768 GB of usable memory with one installed microprocessor, and 1536 GB of usable memory with two installed microprocessors (using 64 GB DIMMs).
  • Independent-channel mode: Independent-channel mode provides a maximum of 384 GB of usable memory with one installed microprocessor, and 768 GB of usable memory with two installed microprocessors (using 32 GB DIMMs).

  • 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.

    The memory rank sparing mode requires an even number of DIMMs. If your server has an odd number of DIMMs installed, ensure that you disable the memory rank sparing mode from the Memory menu in Setup Utility. See Using the Setup utility.

    Note
    After disabling the memory rank sparing mode, if a message prompts that the memory configuration is not valid, restart the IMM2. Alternatively, you can turn off the server, disconnect it from and then reconnect it to ac power, and then turn on the server again.
    The following notes describe additional information that you must consider when you select rank-sparing memory mode:
    • Rank-sparing on one channel is independent of the sparing on all other channels.
    • To use rank sparing, install at least one DIMM pair for each microprocessor. If a channel has only one DIMM and it is single-rank or dual-rank, do not attempt to use memory sparing.
    • The effective memory that is available to the system is less than what is installed.
    • You can use the Setup utility to determine the status of the DIMM ranks.
  • Mirrored-channel mode: In mirrored-channel mode, memory is installed in pairs. Each DIMM in a pair must be identical in size and architecture. The channels are grouped in pairs with each channel receiving the same data. One channel is used as a backup of the other, which provides redundancy. The memory contents on channel A are duplicated in channel B, and the memory contents of channel C are duplicated in channel D. The effective memory that is available to the system is only half of what is installed.

One DIMM for each microprocessor is the minimum requirement. However, for optimal performance, install DIMMs in sets of four so that you distribute memory equally across all four channels. If two microprocessors are installed, distribute memory across all channels and equally between the microprocessors.

Install DIMMs in order as indicated in the following table for independent-channel mode.
Table 4. DIMM population sequence for independent-channel mode.

The independent-channel mode DIMM population sequence table is a five-column table where the rows indicate the DIMM installation sequence for independent-channel mode. Column 1 lists the DIMM installation order. Column 2 indicates the DIMM connectors to populate for systems with one microprocessor. Column 3 indicates the number of DIMMs per channel for systems with one microprocessor. Column 4 indicates the DIMM connectors to populate for systems with two microprocessors. Column 5 indicates the number of DIMMs per channel for systems with two microprocessors.

Number of installed DIMMs1 microprocessor installed2 microprocessors installed
DIMM slot numberDIMMs per channelDIMM slot numberDIMMs per channel
14141
2916
319
41221
5521
6813
7212
81124
96352
10717
1138
121020
13Not used - maximum of 12 DIMMs in systems with 1 microprocessor2
1414
1511
1623
1763
1818
197
2019
213
2215
2310
2422
Install DIMMs in order as indicated in the following table for rank-sparing mode.
Table 5. DIMM population sequence for rank-sparing mode.

The rank-sparing mode DIMM population sequence table is a five-column table where the rows indicate the DIMM installation sequence for rank-sparing mode. Column 1 lists the DIMM pair installation order. Columns 2 and 3 indicate the DIMM connectors to populate for 2 DIMMs per channel. Columns 4 and 5 indicate the DIMM connectors to populate for 3 DIMMs per channel.

DIMM pair installation order2 DIMMs per channel3 DIMMs per channel
1 microprocessor installed2 microprocessors installed1 microprocessor installed2 microprocessors installed
14 and 54 and 54, 5, and 64, 5, and 6
28 and 920 and 217, 8, and 919, 20, and 21
31 and 28 and 91, 2, and 37, 8, and 9
411 and 1216 and 1710, 11, and 1216, 17 and 18
5n/a1 and 2n/a1, 2, and 3
623 and 2422, 23, and 24
711 and 1210, 11, and 12
813 and 1413, 14, and 15

Install DIMMs in order as indicated in the following table for mirrored-channel mode.

Table 6. DIMM population sequence for mirrored-channel mode.

The mirrored-channel mode DIMM population sequence table is a five-column table where the rows indicate the DIMM installation sequence for mirrored-channel mode. Column 1 lists the DIMM installation order. Column 2 indicates the DIMM connectors to populate for systems with one microprocessor. Column 3 indicates the number of DIMMs per channel for systems with one microprocessor. Column 4 indicates the DIMM connectors to populate for systems with two microprocessors. Column 5 indicates the number of DIMMs per channel for systems with two microprocessors.

DIMM pair1 microprocessor installed2 microprocessors installed
DIMM slot numbersDIMMs per channelDIMM slot numbersDIMMs per channel
14 and 1114 and 111
29 and 12121 and 241
32 and 5129 and 121
48 and 11113 and 161
53 and 6132 and 512
67 and 10120 and 231
7none8 and 111
8none14 and 171
9none3 and 613
10none19 and 221
11none7 and 101
12none15 and 181
  1. For mirrored-channel mode, the DIMM pair must be identical in size, type, and rank count.

To install a DIMM, complete the following steps:

Note
Remove or install DIMMs for one microprocessor at a time.

  1. Remove the cover (see Removing the compute node cover).
  2. Read the documentation that comes with the DIMM.
  3. Remove the air baffle installed over the DIMM connector.

    Graphic illustrating air baffles remove and install
  4. Locate the DIMM connectors (see System-board connectors). Determine in which DIMM connector you want to install the DIMM.
  5. Touch the static-protective package that contains the DIMM to any unpainted metal surface on the Lenovo Flex System chassis or any unpainted metal surface on any other grounded rack component in the rack in which you are installing the DIMM for at least 2 seconds; then, remove the DIMM from its package.
    Graphic illustrating the removal/install of DIMMs in the node
  6. Make sure that both retaining clips on the DIMM connector are in the open position.
    Attention
    To avoid breaking the retaining clips or damaging the DIMM connector, handle the clips gently.
    Note
    The retaining clips for adjacent DIMM connectors of microprocessor one and microprocessor two can not be open at the same time. Remove or install the DIMMs for each microprocessor one at a time.

    Graphic illustrating the DIMM retaining clips
    Note
    If necessary due to space constraints, you can use a pointed tool to open the retaining clips. Place the tip of the tool in the recess on the top of the retaining clip; then, carefully rotate the retaining clip away from the DIMM connector.
  7. Turn the DIMM so that the DIMM keys align correctly with the DIMM connector on the system board.
  8. Press the DIMM into the DIMM connector. The retaining clips lock the DIMM into the connector.
  9. Make sure that the small tabs on the retaining clips engage the notches on the DIMM. If there is a gap between the DIMM and the retaining clips, the DIMM has not been correctly installed. Press the DIMM firmly into the connector, and then press the retaining clips toward the DIMM until the tabs are fully seated. When the DIMM is correctly installed, the retaining clips are parallel to the sides of the DIMM.

    Graphic illustrating air baffles remove and install
    Note
    Retaining clips on the DIMM connectors must be in the closed position to install the air baffles.
  10. Install the air baffle over the DIMM connector.
    Attention
    To maintain proper system cooling, do not operate the compute node without air baffles installed over the DIMM connectors.
After you install the DIMM, complete the following steps:
  1. Install the cover onto the compute node (see Installing the compute node cover for instructions).
  2. Install the compute node into the chassis (see Installing a compute node in a chassis for instructions).