Product guide

IBM Flex System x440 Compute Node 10
Memory options
IBM DDR3 memory is compatibility tested and tuned for optimal performance and throughput. IBM
memory specifications are integrated into the light path diagnostic tests for immediate system
performance feedback and optimum system uptime. From a service and support standpoint, IBM memory
automatically assumes the IBM system warranty, and IBM provides service and support worldwide.
The x440 supports DDR3 memory. The compute node supports up to 48 DIMMs when four processors are
installed, with 12 DIMMs for each processor. Each processor has four memory channels, and there are
three DIMMs per channel.
The following rules apply when selecting the memory configuration:
The server supports UDIMMs, RDIMMs and LRDIMMs.

Mixing different types of memory (eg RDIMMs and LRDIMMs) is not supported.

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 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 same
electrical load on a memory bus as a single-rank RDIMM).
The maximum quantity of DIMMs that can be installed in the server depends on the number of

processors installed. The following table shows the maximum when all four processors are installed.
When two processors are installed, the maximum quantity supported is a half of the quantity that is
shown.
All DIMMs in the server operate at the same speed, which is determined as the lowest value of:

The memory speed that is supported by the specific processor.

The lowest of maximum operating speeds for the selected memory configuration that depends on

rated speed, operating voltage, and quantity of DIMMs per channel, as shown under "Max.
operating speed" section in the table.