IBM System x3550 M3 Type 4254 Installation And User Manual page 73

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 7. Maximum memory installation using ranked DIMMs
Number of DIMMs DIMM type
12 Single-rank UDIMMs
12 Dual-rank UDIMMs
18 Single-rank RDIMMs
18 Dual-rank RDIMMs
18 Dual-rank RDIMMs
18 Dual-rank RDIMMs
12 Quad-rank RDIMMs
18 Dual-rank RDIMMs
v 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 288 GB of
system memory using RDIMMs.
For 32-bit operating systems only: Some memory is reserved for various
system resources and is unavailable to the operating system. The amount of
memory that is reserved for system resources depends on the operating system,
the configuration of the server, and the configured PCI devices.
DIMM size Total memory
2 GB 24 GB
4 GB 48 GB
2 GB 36 GB
2 GB 36 GB
4 GB 72 GB
8 GB 144 GB
16 GB 192 GB
16 GB 288 GB
Chapter 2. Installing optional devices
57