Independent Memory Mode - IBM System x3850 X6 Installation And Service Manual

Independent memory mode

Use this information for notes and details about independent memory mode and
DIMM installation sequence.
Independent memory mode supports the memory mirroring and memory rank
sparing features. When you use independent memory mode, consider the
following. For more information and notes about installing DIMMs, see "Installing
a memory module" on page 47. For more information about DIMM population
sequence, see "Memory mirroring in independent memory mode" on page 56 and
"Memory rank sparing in independent mode" on page 58..
v Independent memory mode provides the most efficient performance.
v You can populate DIMMs in any order and there are no matching requirements.
v When you operate in this mode, the memory channel operates at twice the
v Single-device data correction (SDDC) is supported for x4 SDRAM technology.
The following table lists the maximum memory speed supported based on the type
of ranked DIMM and the voltage at which the DIMM runs.
Note: The DIMM operating speed and voltage can vary depending on the
microprocessor installed, memory installed, and performance mode that is set in
the Setup Utility.
Table 11. Memory speeds and configurations based on ranked DIMM type and voltage for independent memory
mode
DIMM rank,
type, and DIMM
technology capacity
Single-rank x4 4 GB
RDIMM - 2 Gb
(1600 MHz)
Single-rank x4 8 GB
RDIMM - 4 Gb
(1600 MHz)
Dual-rank x4 16 GB
RDIMM - 4 Gb
(1600 MHz)
Quad-rank x4 32 GB
LRDIMM - 4 Gb
(1600 MHz)
Octal-rank x4 64 GB
(8-rank) LRDIMM
- 4 Gb (1333
MHz)
The following table lists the installation sequence for independent mode:
However, the DIMM population sequence in the following table will provide the
best performance when operating in the supported memory modes.
DDR3 data rate.
1 DIMM per DDR3
channel
1.35 V 1.50 V
1333 1333
1333 1333
1333 1333
1333 1333
1333 1333
2 DIMMs per DDR3
channel
1.35 V 1.50 V
1333 1333
1333 1333
1333 1333
1333 1333
1333 1333
Chapter 2. Installing optional devices
3 DIMMs per DDR3
channel
1.35 V 1.50 V
1066 1333
1066 1333
1066 1333
1333 1333
1333 1333
55