Memory module installation

The following notes describe the types of dual inline memory modules (DIMMs) that the server supports and other information that you must consider when you install DIMMs.

Confirm that the server supports the DIMM that you are installing, see https://static.lenovo.com/us/en/serverproven/index.shtml.
When you install or remove DIMMs, the server configuration information changes. When you restart the server, the system displays a message that indicates that the memory configuration has changed.
The server supports only industry-standard double-data-rate 3 (DDR3) - 1600 or 1866 MHz (depending on the configuration) , synchronous dynamic random-access memory (SDRAM) registered dual inline memory modules (DIMMs) with error correcting code (ECC).
The specifications of a DDR3 DIMM are on a label on the DIMM, in the following format.
gggeRxff-PC3-wwwwwm-aa-bb-cc-dd
where:
- ggg is the total capacity of the DIMM (for example, 1GB, 2GB, or 4GB)
- eis the number of ranks
  - 1 = single-rank
  - 2 = dual-rank
- x ff is the device organization or bit width (for example, x4, x8, or x16)
  - 4 = x4 organization (4 DQ lines per SDRAM)
  - 8 = x8 organization
  - 16 = x16 organization
- wwwww is the DIMM bandwidth, in MBps
  - 12800 = 12.80 GBps PC3-1600 SDRAMs, 8-byte primary data bus)
  - 14900 = 14.93 GBps PC3-1866 SDRAMS, 8-byte primary data bus)
- m is the DIMM type
  - E = Unbuffered DIMM (UDIMM) with ECC (x72-bit module data bus)
  - R = Registered DIMM (RDIMM)
  - U = Unbuffered DIMM with no ECC (x64-bit primary data bus)
  - L = Load Reduction DIMM (LR-DIMM)
- aa is the DDR3 SDRAM 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 xxx nRxxx PC3-xxxxx-xx-xx-xx-xx. The numeral in the fourth numerical position indicates whether the DIMM is single-rank (n=1) or dual-rank (n=2).
Do not mix registered and unbuffered DIMMs in the server.
Do not mix load reduced DIMMs with other types of DIMMs in the server.
DO not mix ECC and non-ECC DIMMs in the server.
The server supports 1.35-volt (low-voltage) and 1.5-volt DIMMs.
The server supports a maximum of 16 DIMMs (single-rank and dual-rank) on the base system board.
The DIMM options that are available for the server are 4 GB, 8 GB, 16 GB, and 32 GB (when available).
The server supports memory sparing. Memory sparing reserves memory capacity for failover in the event of a DIMM failure, and the reserved capacity is deducted from the total available memory. Memory sparing provides less redundancy than memory mirroring does. If a predetermined threshold of correctable errors is reached, the contents of the failing DIMM are copied to the spare memory, and the failing DIMM or rank is disabled. To enable memory sparing through the Setup utility, select System Settings > Memory.
The server system board supports a minimum of 4 GB and a maximum of 512 GB of system memory.
Note
The amount of usable memory is reduced depending on the system configuration. A certain amount of memory must be reserved for system resources. To view the total amount of installed memory and the amount of configured memory, run the Setup utility. For additional information, see Configuring the server.

The following table shows the DIMM connectors that are associated with each microprocessor:

Table 1. DIMM connectors associated with each microprocessor.
There are two rows of column headings. The first column is microprocessor. The second column is DIMM connectors associated with the microprocessor.
Microprocessor	DIMM connectors associated with the microprocessor
Microprocessor 1	1 through 8
Microprocessor 2	9 through 16

When you replace a DIMM, the server provides automatic DIMM enablement capability without you having to go to Setup to enable the new DIMM manually.
The maximum operating speed of the server is determined by the slowest DIMM installed in the server.
A minimum of one DIMM must be installed for each microprocessor. For example, you must install a minimum of two DIMMs if the server has two microprocessors installed.
The server comes with a minimum of one DIMM installed in slot 8. When you install additional DIMMs, install them in the order shown in the information in the following tables to optimize system performance.
The server supports independent mode, rank sparing mode, and mirroring mode.

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