IBM System x3550 M5 Type 5463 Installation And Service Manual page 182

v The following rules apply to DDR4 RDIMM speed as it relates to the number of
v The maximum memory speed is determined by the combination of the
v In two-DIMM-per-channel configuration, the server automatically operates with
v The server supports a maximum of 24 single-rank, dual-rank RDIMMs or 24
v The following table shows an example of the maximum amount of memory that
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IBM System x3550 M5 Type 5463: Installation and Service Guide
v 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
L = Load Reduction DIMM (LRDIMM)
R = Registered DIMM (RDIMM)
- 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).
RDIMMs in a channel:
– When you install 1 RDIMM per channel, the memory runs at 1600 MHz
– When you install 2 RDIMMs per channel, the memory runs at 1860 MHz
– When you install 3 RDIMMs per channel, the memory runs at 2133 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
microprocessor, DIMM speed, DIMM type, Operating Modes in UEFI settings,
and the number of DIMMs installed in each channel.
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 RDIMMs or LRDIMMs will function at 1.5 V.
quad-rank LRIMMs.
you can install using ranked DIMMs or load-reduced DIMMs:
Table 24. Maximum memory installation
Number of DIMMs DIMM type
24 Single-rank RDIMM
24 Dual-rank RDIMM
24 Dual-rank RDIMM
16 Quad-rank LRDIMM 32 GB
24 Quad-rank LRDIMM 64 GB
Size Total memory
4 GB 96 GB
8 GB 192 GB
16 GB 384 GB
768 GB
1536 GB