Product guide

IBM Flex System X6 Compute Nodes Product Guide 13
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 X6 Compute Nodes support DDR3 memory operating at speeds up to 1600 MHz with 24 DIMMs per
processor:
A 2-socket configuration supports up to 48 DIMMs.

A 4-socket scaled configuration supports up to 96 DIMMs.

An 8-socket configuration supports up to 192 DIMMs.

The following table lists the memory options that are available for X6 Compute Nodes.
Table 6. Memory options
Part number Feature code Description Maximum
supported
Models
where used
RDIMMs
00D5024* A3QE 4GB (1x4GB, 1Rx4, 1.35V) PC3L-12800
CL11 ECC DDR3 1600MHz LP RDIMM
48 (24 per CPU) -
00D5036 A3QH 8GB (1x8GB, 1Rx4, 1.35V) PC3L-12800
CL11 ECC DDR3 1600MHz LP RDIMM
48 (24 per CPU) -
46W0672 A3QM 16GB (1x16GB, 2Rx4, 1.35V) PC3L-12800
CL11 ECC DDR3 1600MHz LP RDIMM
48 (24 per CPU) All models
LRDIMMs
46W0676* A3SR 32GB (1x32GB, 4Rx4, 1.35V) PC3L-12800
CL11 ECC DDR3 1600MHz LP LRDIMM
48 (24 per CPU) -
46W0741*† A451 64GB (1x64GB, 8Rx4, 1.35V) PC3-10600
DDR3 1333MHz LP LRDIMM
48 (24 per CPU) -
* Not allowed if any eXFlash DIMMs are installed (when supported).
† 64 GB LRDIMMs are only supported in 2-socket or 4-socket configurations.
Each processor has four memory channels to memory buffers that are implemented using Scalable
Memory Interface generation 2 (SMI2) chips. Each memory buffer has two memory channels and
implements three DIMMs per channel.
The following rules apply when selecting the memory configuration:
The X6 node supports RDIMMs and LRDIMMs.

Mixing of RDIMM and LRDIMM is not supported.

4 GB RDIMMs and LRDRIMMs cannot be used with IBM eXFlash DIMMs (when 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 processors support two memory modes: Performance mode and RAS (or lockstep) mode. In

RAS (lockstep) mode, DIMMs must be installed in a pair, and the SMI link operates at the speed of
the memory bus.