Installing a DIMM

Use this information to install a DIMM.

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 replacing a DIMM as a result of a DIMM failure, you might have to reenable the DIMM. To reenable the DIMM, complete the following steps:

1. Verify that the amount of installed memory is the expected amount 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.
   • For more information about the CMM sol command, see the "Flex System Chassis Management Module: Command-Line Interface Reference Guide".
   • For more information about Flex System Manager management software, see the "Flex System Manager Software: Installation and Service Guide".
2. Run the Setup utility to reenable the DIMMs (see Using the Setup utility for more information).

The compute node supports low-profile (LP) DDR3 DIMMs with error-correcting code (ECC) in 2 GB, 4 GB, 8 GB, and 16 GB capacities.

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

The compute node has six memory channels with two dual inline memory module (DIMM) connectors each, for a total of 12 DIMM connectors. Three channels are associated with each of the two microprocessors. The following table lists the channels that are associated with each microprocessor and the DIMM connectors in each channel.

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.

Microprocessor	Memory channel	DIMM connectors
Microprocessor 1	A	1 and 2
	B	3 and 4
	C	5 and 6
Microprocessor 2	D	11 and 12
	E	9 and 10
	F	7 and 8

Depending on the memory mode that is set in the Setup utility, the compute node can support a minimum of 2 GB and a maximum of 192 GB of system memory.

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

• You cannot mix UDIMMs and RDIMMs in the same compute node.
• You cannot mix non-mirrored-channel and mirrored-channel modes.
• A total of eight ranks on each channel is supported.
• If a quad-rank DIMM is installed, install it in the connector at the end of the memory channel.
• If a channel has one or more quad-rank DIMMs, only two DIMMs per channel is supported.
• Populate the DIMMs on microprocessor 1 first and populate the DIMM on the closest channel to the microprocessor first.
• Populate the farthest DIMM slot on the channel first.
• Different memory modes require a different population order.
• DIMM slots 2, 4, 6, 7, 9 and 11 must be populated (actual DIMM or DIMM filler).
• DIMM slots 1,3, 5, 8, 10 and 12 do not require a DIMM filler.

There are three memory modes:

• Independent-channel mode: Independent-channel mode provides a maximum of 96 GB of usable memory with one installed microprocessor, and 192 GB of usable memory with two installed microprocessors (using 16 GB DIMMs). See Independent-channel mode for additional information.
• 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 are 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. See Rank-sparing mode for additional information.
  The following notes describe additional information that you must consider when you select rank-sparing memory mode:

  • Memory sparing on one channel is independent of the sparing on all other channels.
  • You can use the Setup utility to determine the status of the DIMM ranks.
  • If only one DIMM is present in a channel and the DIMM is dual or single rank, then sparing mode should not be enabled.
• Mirrored-channel mode: In mirrored-channel mode, memory is installed in pairs. Each DIMM in a pair must be identical in capacity, type, and rank count. 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. For each microprocessor, the memory contents on channel 2 are duplicated in channel 3, channel 1 is unused. The effective memory that is available to the system is only half of what is installed. See Mirrored-channel mode for additional information.

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 channels. If two microprocessors are installed, distribute memory across all channels and equally between the microprocessors. Install DIMMs in the order as indicated in the following table for independent-channel mode and rank-sparing mode.

To install a DIMM, complete the following steps:

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.
   
   
   
4. Locate the DIMM connectors (see System-board connectors). Determine which DIMM connector you want to install the DIMM in.
5. Touch the static-protective package that contains the DIMM to any unpainted metal surface on the 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.
   
   
6. Make sure that both retaining clips on the DIMM connector are in the open position.
7. Turn the DIMM so that the DIMM keys align correctly with the DIMM connector on the system board.
   Attention

   To avoid breaking the retaining clips or damaging the DIMM connector, handle the clips gently.
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.
   
   
   
10. Install the air baffle over the DIMM connector.
    Attention

    To maintain proper system cooling, ensure correct placement of the air baffles. Do not operate the compute node without air baffles installed over the DIMM connectors.