Configuration Notes

When putting together a Nehalem system, the following configuration parameters should be followed to ensure maximum memory bandwidth.

For Dual-Processor systems:

• Use the same number of memory modules on both processors.

For ALL systems:

• All memory modules should be the same model number. This is a stability issue.
• If possible, u se at least one module per channel on each processor.
• Beyond those modules necessary to put one onto each memory channel, use as few modules as possible.
• Use dual-rank modules.
• Use the fastest memory your processor is rated for, or faster. This is to provide maximum flexability in the future.
• Use the same number of modules on all channels. With some memory configurations, and some motherboards, this is not possible, but a balanced memory configuration will provide the best possible bandwidth.
• Follow the manufacturer's instructions on chanel population. During the benchmarks performed for this paper, as much as a 25% drop in memory bandwidth was notices when the channels were inadvertantly populated in the wrong order.

It should be noted that memory bandwidth had no significant impact on the benchmark we used above (Cinebench), but there are workloads where memory bandwidth will have an effect. The most common is virtualization. Additionally, some HPC (High Performance Computing) workloads are VERY sensative to memory bandwidth.

Bibliography

In addition to the links above, the Intel Xeon Processor 5500 Series Datasheet, Volume 2, specifically chapter 3, was very useful here, along with Intel's Specification Updates for the various processors.

Some information from the Dell Enterprise Center - TechCenter Wiki - Nehalem and Memory Configurations was useful.

The following table lists the motherboards that were used in this project.

The following table lists the memory that was used in this project. There were no issues with any one type of this memory in the boards. As there were occasional minor stability issues when memory was mixed, it is suggested that only a single model number of memory be used in a system.

The Registered memory was not used in the single-socket system.

NOTE: Although the Super-Talent memory worked correctly where used in these tests, other testing has shown incompatabilities. For this reason, combined with the overall poor support we received from the manufacturer, we do not suggest or advise that Super-Talent memory be used for new systems.