All DIMMs in all processor memory channels operate at the same speed, which is determined as the
lowest value of:
The memory speed supported by the specific processor.
The lowest of maximum operating speeds for the selected memory configuration that
depends on the rated speed, operating voltage, and quantity of DIMMs per channel, as
shown under the "Maximum operating speed" section in Table 5.
The following memory protection technologies are supported:
ECC
Chipkill (for x4-based memory DIMMs)
Memory mirroring
Memory rank sparing
Chipkill works only in independent channel mode (the default is operational mode) and supports only x4-
based memory DIMMs.
If memory mirroring is used, then DIMMs must be installed in pairs (a minimum of one pair per each
processor, and a maximum of two pairs per processor), and both DIMMs in a pair must be identical in type
and size.
If memory rank sparing is used, then two single-rank or dual-rank DIMMs must be installed per populated
channel (the DIMMs do not need to be identical). In rank sparing mode, one rank of a DIMM in each
populated channel is reserved as spare memory. The size of a rank varies depending on the DIMMs
installed.
Chipkill, memory mirroring, and memory rank sparing modes are mutually exclusive. Only one operational
memory mode can be enabled on a server, and it is a system-wide setting.
The following table shows the characteristics of the supported DIMMs. Table cells highlighted with a gray
background indicate when the combination of DIMM voltage and the number of DIMMs per channel still
allows the DIMMs to operate at a rated speed.
Table 5. Maximum memory speeds (Part 1: RDIMMs)
DIMM type
Specification
RDIMM
Rank
Single rank
Dual rank
Quad
rank
Rated speed
1333 MHz
1600
MHz
1333 MHz
1600
MHz
1066
MHz
Rated voltage
1.35 V
1.5 V
1.35 V
1.5 V
1.35 V
Operating voltage
1.35 V
1.5 V
1.5 V
1.35 V
1.5 V
1.5 V
1.35 V
Max quantity*
12
12
12
12
12
12
12
Largest DIMM
4 GB
4 GB
4 GB
16 GB
16 GB
8 GB
8 GB
Max memory capacity
48 GB
48 GB
48 GB
192 GB
192 GB
96 GB
96 GB
Max memory at rated speed
48 GB
48 GB
48 GB
192 GB
192 GB
96 GB
NS**
Maximum operating speed (MHz)
1 DIMM per channel
1333
MHz
1333
MHz
1600
MHz
1333
MHz
1333
MHz
1600
MHz
800 MHz
2 DIMMs per channel
1333
MHz
1333
MHz
1600
MHz
1333
MHz
1333
MHz
1600
MHz
800 MHz
* Maximum quantity supported is shown for two processors installed. When one processor is installed, the maximum quantity
supported is a half of what is shown.
** Rated speed is not supported. Memory DIMMs always operate at speeds lower than rated.
System x3630 M4 (E5-2400)
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