Datasheet

IBM Flex System x240 Compute Node 9
The following rules apply when selecting the memory configuration:
Mixing 1.5 V and 1.35 V DIMMs in the same server is supported. In such a case all DIMMs operate at

1.5 V.
The maximum number of ranks supported per channel is eight.

The maximum quantity of DIMMs that can be installed in the server depends on the number of CPUs,

DIMM rank, and operating voltage, as shown in the "Max. qty supported" row in the following table.
The shaded cells indicate that the DIMM type supports the maximum number of DIMMs (24 for the
x240)
All DIMMs in all CPU memory channels operate at the same speed, which is determined as the

lowest value of:
Memory speed supported by specific CPU

Lowest maximum operating speed for the selected memory configuration that depends on rated

speed, as shown under the "Max. operating speed" section in the following table. The shaded
cells indicate that the speed indicated is the maximum that the DIMM allows.
The following table shows the maximum memory speeds that are achievable based on the installed
DIMMs and the number of DIMMs per channel. The table also shows maximum memory capacity at any
speed supported by the DIMM and maximum memory capacity at rated DIMM speed. In the table, cells
highlighted with a grey background indicate when the specific combination of DIMM voltage and number
of DIMMs per channel still allows the DIMMs to operate at rated speed.
Table 4. Maximum memory speeds
Specification UDIMMs RDIMMs LRDIMMs
Rank Dual rank Single rank Dual rank Quad rank Quad rank
Rated speed 1333 MHz 1333 MHz 1600
MHz
1333 MHz 1600
MHz
1066 MHz 1333 MHz
Rated voltage 1.35 V 1.35 V 1.5 V 1.35 V 1.5 V 1.35 V 1.35 V
Operating
voltage
1.35 V 1.5 V 1.35 V 1.5 V 1.5 V 1.35 V 1.5 V 1.5 V 1.35 V 1.5 V 1.35 V 1.5 V
Max quantity* 16 16 16 24 24 16 24 24 8 16 24 24
Largest DIMM 4 GB 4 GB 4 GB 4 GB 4 GB 16 GB 16 GB 16 GB 32 GB 32 GB 32 GB 32 GB
Max memory
capacity
64 GB 64 GB 64 GB 96 GB 96 GB 256 GB 384 GB 384 GB 256 GB 512 GB 768 GB 768 GB
Max memory
at rated speed
64 GB 64 GB 64 GB 64 GB 64 GB 256 GB 256 GB 256 GB 128 GB 256 GB 768 GB 512 GB
Maximum operating speed (MHz)
1 DIMMs
per channel
1333
MHz
1333
MHz
1333
MHz
1333
MHz
1600
MHz
1333
MHz
1333
MHz
1600
MHz
800
MHz
1066
MHz
1066
MHz
1333
MHz
2 DIMMs
per channel
1333
MHz
1333
MHz
1333
MHz
1333
MHz
1600
MHz
1333
MHz
1333
MHz
1600
MHz
NS** 800
MHz
1066
MHz
1333
MHz
3 DIMMs
per channel
NS** NS** NS** 1066
MHz
1066
MHz
NS** 1066
MHz
1066
MHz
NS** NS** 1066
MHz
1066
MHz
* The maximum quantity supported is shown for two processors installed. When one processor is installed, the
maximum quantity supported is a half of that shown.
** NS = Not supported. When three 1.35 V DIMMs are installed in a memory channel, they operate at 1.5 V instead.