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v The maximum operating speed of the server is determined by the slowest DIMM in the server.
v If you install a pair of DIMMs in DIMM connectors 2 and 5, the size and speed of the DIMMs that you
install in DIMM connectors 2 and 5 must match each other. How ever, they do not have to be the same
size and speed as the DIMMs that are installed in DIMM connectors 1 and 4.
v You can use compatible DIMMs from various manufacturers in the same pair.
v 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.
v The specifications of a DDR3 DIMM are on a label on the DIMM, in the following format.
ggg eRxff-PC3-wwwwwm-aa-bb-cc
where:
ggg is the total capacity of the DIMM (for example, 1GB, 2GB, or 4GB)
e is the number of ranks
1 = single-rank
2 = dual-rank
4 = quad-rank
ff is the device organization (bit width)
4 = x4 organization (4 DQ lines per SDRAM)
8 = x8 organization
16 = x16 organization
wwwww is the DIMM bandwidth, in MBps
8500 = 8.53 GBps (PC3-1066 SDRAMs, 8-byte primary data bus)
10600 = 10.66 GBps (PC3-1333 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)
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) or dual-rank (n=2).
The following sections provide additional information specific to unbuffered and registered DIMMs that
you must consider.
Unbuffered DIMMs (UDIMMs)
The following notes provide information that you must configure when you install UDIMMs:
v The memory channels run at the fastest common frequency of the installed DIMMs.
v Do not use both UDIMMs and RDIMMs in the same server.
v Using ECC and non-ECC UDIMMs in the server will cause the server to run in non-ECC mode.
v The UDIMM options that are available for the server are 1 GB, 2 GB, and 4 GB (when available)
memory DIMMs.
v You can install a maximum of 16 GB of memory in some server models when you use UDIMMs.
v The server supports up to two single-rank or dual-rank UDIMMs per channel.
Chapter 6. Replacing FRUs
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