IBM System x3550 M3 Type 4254 Installation And User Manual page 69

- 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)
- 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 PC3-xxxxx-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).
v The following rules apply to DDR3 DIMM speed as it relates to the number of
DIMMs in a channel:
– When you install 1 DIMM per channel, the memory runs at 1333 MHz
– When you install 2 DIMMs per channel, the memory runs at 1066 MHz
– When you install 3 DIMMs per channel, the memory runs at 800 MHz
– All channels in a server run at the fastest common frequency
– Do not install registered and unbuffered DIMMs in the same server
v The maximum memory speed is determined by the combination of the
microprocessor, DIMM speed, and the number of DIMMs installed in each
channel.
v In two-DIMM-per-channel configuration, a server with an Intel Xeon X5600
series microprocessor automatically operates with a maximum memory speed of
up to 1333 MHz when one of the following conditions is met:
– Two 1.5 V single-rank or dual-rank RDIMMs are installed in the same
channel. In the Setup utility, Memory speed is set to Max performance mode
– Two 1.35 V single-rank or dual-ranl RDIMMs 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
will function at 1.5 V
v The server supports a maximum of 18 single-rank or dual-rank RDIMMs. The
server supports up to 12 single-rank or dual-rank UDIMMs or quad-rank
RDIMMs.
v The server supports three single-rank or dual-rank DIMMs per channel. The
server supports a maximum of two quad-rank RDIMMs per channel. The
following table shows an example of the maximum amount of memory that you
can install using ranked DIMMs:
Table 9. Maximum memory installation using ranked DIMMs
Number of DIMMs DIMM type
12 Single-rank UDIMMs 2 GB
12 Dual-rank UDIMMs
18 Single-rank RDIMMs 2 GB
18 Dual-rank RDIMMs
18 Dual-rank RDIMMs
18 Dual-rank RDIMMs
12 Quad-rank RDIMMs
DIMM size Total memory
24 GB
4 GB 48 GB
36 GB
2 GB 36 GB
4 GB 72 GB
8 GB 144 GB
16 GB 192 GB
Chapter 2. Installing optional devices
55