Installing a memory module - Lenovo System x3550 M4

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

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), 1066, 1333, 1600, or 1866 MHz, PC3-8500, PC3-10600, PC3-12800, or PC3-14900 registered or unbuffered, 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 server.
- The specifications of a DDR3 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 = 1.5 V specified
    
    L = 1.35 V specified, 1.5 V operable
    Note: Values for these voltages are "specified" which means the device characteristics such as timing are supported at this voltage. Values are "operable" which means that the devices can be operated safely at this voltage. However, device characteristics such as timing may not be guaranteed. All devices must be "tolerant" of the highest DDR3 nominal voltage of 1.5 V, meaning that they may not operate at 1.5 V but may be powered at that voltage without damage to the devices.
  - wwwww is the DIMM bandwidth, in MBps
    
    6400 = 6.40 GBps (DDR3-800 SDRAMs, 8-byte primary data bus)
    
    8500 = 8.53 GBps (DDR3-1066 SDRAMs, 8-byte primary data bus)
    
    10600 = 10.66 GBps (DDR3-1333 SDRAMs, 8-byte primary data bus)
    
    12800 = 12.80 GBps (DDR3-1600 SDRAMs, 8-byte primary data bus)
    
    14900 = 14.93 GBps (DDR3-1866 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 DDR3 RDIMM speed as it relates to the number of RDIMMs in a channel:
- When you install 1 RDIMM per channel, the memory runs at 1866 MHz
- When you install 2 RDIMMs per channel, the memory runs at 1600 MHz
- When you install 3 RDIMMs per channel, the memory runs at 1066 MHz
- All channels in a server run at the fastest common frequency
- Do not install registered, unbuffered, 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 server 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 UDIMMs, 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 server supports a maximum of 16 dual-rank UDIMMs. The server supports up to two UDIMMs per channel.
The server supports a maximum of 24 single-rank, dual-rank, or 16 quad-rank RDIMMs. The server does not support three quad-rank RDIMMs in the same channel.

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
Number of DIMMs	DIMM type	DIMM size	Total memory
16	Dual-rank UDIMM	4 GB	64 GB
24	Single-rank RDIMM	2 GB	48 GB
24	Single-rank RDIMM	4 GB	96 GB
24	Dual-rank RDIMM	4 GB	96 GB
24	Dual-rank RDIMM	8 GB	192 GB
24	Dual-rank RDIMM	16 GB	384 GB
16	Quad-rank RDIMM	8 GB	128 GB
24	Quad-rank LRDIMM	32 GB	768 GB

The UDIMM option that is available for the server is 4 GB. The server supports a minimum of 4 GB and a maximum of 64 GB of system memory using UDIMMs.
The RDIMM options that are available for the server are 2 GB, 4 GB, 8 GB, and 16 GB. The server supports a minimum of 2 GB and a maximum of 384 GB of system memory using RDIMMs.
The LRDIMM option that is available for the server is 32 GB. The server supports a minimum of 32 GB and a maximum of 768 GB of system memory using LRDIMMs.
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.
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. However, to improve system performance, install a minimum of four DIMMs for each microprocessor.
DIMMs in the server must be the same type (RDIMM, UDIMM, or LRDIMM) to ensure that the server 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:

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.
DIMM slots 13-24 are reserved for microprocessor 2; thus, DIMM slots 13-24 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