Installing a memory module

The following notes describe the types of DIMMs that the compute node supports and other information that you must consider when you install DIMMs.

• When you install or remove DIMMs, the compute node configuration information changes. When you restart the compute node, the system displays a message that indicates that the memory configuration has changed.
• The compute node supports only industry-standard double-data-rate 4 (DDR4), 1600, 1866, 2133, or 2400 MHz, PC4-12800, PC4-14900, PC4-17000, or PC4-19200 registered or load deduction, synchronous dynamic random-access memory (SDRAM) dual inline memory modules (DIMMs) with error correcting code (ECC). See the Lenovo ServerProven website for a list of supported memory modules for the compute node.
  • The specifications of a DDR4 DIMM are on a label on the DIMM, in the following format.

    gggggeRxff PC3v-wwwwwm-aa-bb-ccd

    where:

    • ggggg is the total capacity of the DIMM (for example, 1 GB, 2 GB, or 4 GB)
    • eR is the number of ranks
      • 1R = single-rank
      • 2R = dual-rank
      • 4R = quad-rank
    • xff is the device organization (bit width)
      • x4 = x4 organization (4 DQ lines per SDRAM)
      • x8 = x8 organization
      • x16 = x16 organization
    • v is the SDRAM and support component supply voltage (VDD)
      • Blank = 1.2 V specified
    • wwwww is the DIMM bandwidth, in MBps
      • 12800 = 12.80 GBps (DDR4-1600 SDRAMs, 8-byte primary data bus)
      • 14900 = 14.93 GBps (DDR4-1866 SDRAMs, 8-byte primary data bus)
      • 17000 = 17.00 GBps (DDR4-2133 SDRAMs, 8-byte primary data bus)
    • m is the DIMM type
      • E = Unbuffered DIMM (UDIMM) with ECC (x72-bit module data bus)
      • L = Load Reduction DIMM (LRDIMM)
      • R = Registered DIMM (RDIMM)
      • U = Unbuffered DIMM with no ECC (x64-bit primary data bus)
    • aa is the CAS latency, in clocks at maximum operating frequency
    • bb is the JEDEC SPD Revision Encoding and Additions level
    • cc is the reference design file for the design of the DIMM
    • d is the revision number of the reference design of the DIMM

  Note

  To determine the type of a DIMM, see the label on the DIMM. The information on the label is in the format xxxxx nRxxx PC3v-xxxxxx-xx-xx-xxx. The numeral in the sixth numerical position indicates whether the DIMM is single-rank (n=1), dual-rank (n=2), or quad-rank (n=4).
• The following rules apply to DDR4 RDIMM speed as it relates to the number of RDIMMs in a channel (with microprocessors of Intel Xeon E5-26xx v4):
  • When you install 1 RDIMM per channel, the memory runs at 2400 MHz
  • When you install 2 RDIMMs per channel, the memory runs at 2400 MHz (down to 2133 MHz if the RDIMMs are 8 GB dual-rank)
  • When you install 1 LRDIMM per channel, the memory runs at 2400 MHz
  • When you install 2 LRDIMMs per channel, the memory runs at 2133 MHz
  • All channels in a server run at the fastest common frequency
  • Do not install registered and load reduction DIMMs in the same server
• The following rules apply to DDR4 RDIMM speed as it relates to the number of RDIMMs in a channel (with microprocessors of Intel Xeon E5-26xx v3):
  • When you install 1 RDIMM per channel, the memory runs at 2133 MHz
  • When you install 2 RDIMMs per channel, the memory runs at 2133 MHz
  • When you install 1 LRDIMM per channel, the memory runs at 2133 MHz
  • When you install 2 LRDIMMs per channel, the memory runs at 2133 MHz
  • All channels in a server run at the fastest common frequency
  • Do not install registered and load reduction DIMMs in the same server
• The maximum memory speed is determined by the combination of the microprocessor, DIMM speed, DIMM type, Operating Modes in UEFI settings, and the number of DIMMs installed in each channel.
• In two-DIMM-per-channel configuration, the compute node automatically operates with a maximum memory speed of up to 1600 MHz when the following condition is met:
  • Two 1.35 V single-rank, dual-ranl, or quad-rank RDIMMs or LRDIMMs are installed in the same channel. In the Setup utility, Memory speed is set to Max performance and LV-DIMM power is set to Enhance performance mode. The 1.35 V UDIMMs, RDIMMs or LRDIMMs will function at 1.5 V.
• The compute node supports a maximum of 16 single-rank, dual--rank RDIMMs or 16 quad-rank LRIMMs.
• The following table shows an example of the maximum amount of memory that you can install using ranked DIMMs:

  Table 1. Maximum memory installation using ranked DIMMs.

  Four column table documenting the total memory with different configurations.

  Number of DIMMs	DIMM type	DIMM size	Total memory
  16	Single-rank RDIMM	4 GB	64 GB
  16	Single-rank RDIMM	8 GB	128 GB
  16	Dual-rank RDIMM	8 GB	128 GB
  16	Dual-rank RDIMM	16 GB	256 GB
  16	Quad-rank LRDIMM	32 GB	512 GB

• The RDIMM options that are available for the compute node are 4 GB, 8 GB, and 16 GB. The compute node supports a minimum of 4 GB and a maximum of 256 GB of system memory using RDIMMs.
• The LRDIMM option that is available for the server is 32 GB. The compute node supports a minimum of 32 GB and a maximum of 512 GB of system memory using LRDIMMs
• A minimum of one DIMM must be installed for each microprocessor. For example, you must install a minimum of two DIMMs if the compute node has two microprocessors installed. However, to improve system performance, install a minimum of four DIMMs for each microprocessor.
• DIMMs in the compute node must be the same type to ensure that the compute node will operate correctly.
• When you install one quad-rank DIMM in a channel, install it in the DIMM connector furthest away from the microprocessor.

Note

1. You can install DIMMs for microprocessor 2 as soon as you install microprocessor 2; you do not have to wait until all of the DIMM slots for microprocessor 1 are filled.
2. DIMM slots 9-16 are reserved for microprocessor 2; thus, DIMM slots 9-16 are enabled when microprocessor 2 is installed.

The following illustration shows the location of the DIMM connectors on the system board.

Figure 1. DIMM connectors location

The following memory-channel configuration table shows the relationship between the processors, memory channels, and the DIMM connectors.

Table 2. Memory-channel configuration table

Channels	Processor 1 – DIMM connectors	Processor 2 – DIMM connectors
Channel 0	7 and 8	9 and 10
Channel 1	5 and 6	11 and 12
Channel 2	1 and 2	15 and 16
Channel 3	3 and 4	13 and 14

• DIMM installation sequence
  Depending on the server model, the server may come with a minimum of one 4 GB DIMM installed in slot 4. When you install additional DIMMs, install them in the order shown in the following table to optimize system performance.
• Memory rank sparing
  The memory rank sparing feature disables the failed memory from the system configuration and activates a rank sparing DIMM to replace the failed active DIMM.
• Memory mirrored channel
  Memory mirrored channel mode replicates and stores data on two pairs of DIMMs within two channels simultaneously.
• Replacing a memory module
  Use this information to install a DIMM.