Lenovo System x3650 M4 BD Product Manual page 10

Lenovo DDR3 memory is compatibility tested and tuned for optimal System x performance and throughput.
Lenovo memory specifications are integrated into the light path diagnostics for immediate system
performance feedback and optimum system uptime. From a service and support standpoint, Lenovo
memory automatically assumes the system warranty, and Lenovo provides service and support worldwide.
The System x3650 M4 BD supports DDR3 memory. The server supports up to eight DIMMs when one
processor is installed and up to 16 DIMMs when two processors are installed. Each processor has four
memory channels, and there are two DIMMs per channel.
The following rules apply when selecting the memory configuration:
The server supports UDIMMs, RDIMMs, and LRDIMMs.
Mixing different types of memory (UDIMMs, RDIMMs, and LRDIMMs) is not supported.
Mixing 1.5 V and 1.35 V DIMMs is not supported.
The maximum number of ranks per one channel is eight (with the exception of Load Reduced DIMMs
where more than eight ranks are supported because one quad-rank LRDIMM provides the reduced
electrical load on a memory bus).
The maximum quantity of DIMMs that can be installed in the server depends on the number of
processors, DIMM type, rank, and operating voltage, as shown in the "Max. qty supported" row in
Table 5.
All DIMMs in the server operate at the same speed, which is determined as the lowest value of:
Memory speed that is supported by the specific processor.
Lowest of maximum operating speeds for selected memory configuration that depends on
rated speed, operating voltage, and quantity of DIMMs per channel, as shown under
"Maximum operating speed" section in the table.
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 (Parts 1 and 2) shows the characteristics of the supported DIMMs. Tables cells that are
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)
System x3650 M4 BD 10