Product guide

IBM Flex System X6 Compute Nodes Product Guide 14
When RDIMMs are installed, the maximum number of ranks that are supported per channel is eight.

With LRDIMMs, the rank count per channel can be 32 (LRDIMM ranks are only 25% of the electrical
load of an RDIMM rank).
All DIMMs in all processor memory channels operate at the same speed, which is determined as the

lowest value of the following components:
The memory mode used: Performance (independent) mode or RAS (lockstep) mode.
o
Memory speed that is supported by a specific processor.
o
Lowest of maximum operating speeds for selected memory configuration, depending on the rated
o
speed, operating voltage, and quantity of DIMMs per channel, as shown under the “Maximum
operating speed” section in the following table.
The following table shows the characteristics of the supported DIMMs. Tables cells that are highlighted
with a gray background indicate that the server supports higher memory frequencies or larger memory
capacity (or both) than the Intel processor specification defines.
Memory speed: In performance mode, memory channels operate independently, and the SMI2 link
operates at twice the DDR3 speed. In RAS mode, two channels operate synchronously, and the SMI2 link
operates at the DDR3 speed.
Table 7. Maximum memory speeds
DIMM
specification
RDIMM LRDIMM
Rank Single rank Dual rank Quad rank 8-rank
Part numbers 00D5024 (4GB)
00D5036 (8GB)
46W0672 (16GB) 46W0676 (32GB) 46W0741 (64GB)
Rated speed 1600 MHz 1600 MHz 1600 MHz 1333 MHz
Rated voltage 1.35 V 1.35 V 1.35 V 1.35 V
Operating voltage 1.35 V 1.5 V 1.35 V 1.5 V 1.35 V 1.5 V 1.35 V 1.5 V
Max qty supported* 96 96 96 96 96 96 96 96
Max DIMM capacity 8 GB 8 GB 16 GB 16 GB 32 GB 32 GB 64 GB 64 GB
Max memory capacity 0.75 TB 0.75 TB 1.5 TB 1.5 TB 3 TB 3 TB 6 TB 6 TB
Maximum operating speed - Performance mode (2:1 mode - SMI2 link operates at twice the DDR3 speed that
is shown)
1 DIMM per channel 1333 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz
2 DIMMs per channel 1333 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz
3 DIMMs per channel 1066 MHz 1333 MHz 1066 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz
Maximum operating speed - RAS mode (1:1 mode - SMI2 link operates at the DDR3 speed that is shown)
1 DIMM per channel 1333 MHz 1600 MHz 1333 MHz 1600 MHz 1333 MHz 1600 MHz 1333 MHz 1333 MHz
2 DIMMs per channel 1333 MHz 1600 MHz 1333 MHz 1600 MHz 1333 MHz 1600 MHz 1333 MHz 1333 MHz
3 DIMMs per channel 1066 MHz 1333 MHz 1066 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz 1333 MHz
* Maximum quantity that is supported is shown for all the processors that are installed.