Lenovo Flex System x240 Instruction Manual page 14

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.
Mixing of different types of DIMMs (UDIMM , RDIMM and LRDIMM) in the same server is not

supported.
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 two tables (Part 1 and Part 2) show the maximum memory speeds that are achievable
based on the installed DIMMs and the number of DIMMs per channel. The tables also show maximum
memory capacity at any speed supported by the DIMM and maximum memory capacity at rated DIMM
speed. In the tables, cells highlighted with a gray 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 7. Maximum memory speeds (Part 1 - UDIMMs and LRDIMMs)
Specification
Rank
Part numbers
Rated speed
Rated voltage
Operating voltage
Maximum quantity*
Largest DIMM
Max memory capacity
Max memory at rated
speed
Maximum operating speed (MHz)
One DIMM per channel
Two DIMMs per channel
Three DIMMs per channel
* The maximum quantity supported is shown for two processors installed. When one processor is installed, the
maximum quantity supported is half of that shown.
† NS = Not supported. UDIMMs only support up to 2 DIMMs per channel.
Flex System x240 Compute Node (E5-2600 v2)
UDIMMs
Dual rank
00D5012 (4 GB)
00D5016 (8 GB)
1600 MHz
1.35 V
1.35 V
16
8 GB
128 GB
None
1333 MHz
1333 MHz
NS†
46W0761 (32 GB)
1.5 V
16
8 GB
128 GB
128 GB
1600 MHz
1600 MHz
NS†
LRDIMMs
Quad rank
1866 MHz
1.5 V
1.5 V
24
32 GB
768 GB
512 GB
1866 MHz
1866 MHz
1333 MHz
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