Dual rank vs. Single rank memory question

[chuckk281]

Vasyl had some questions regarding memory useage:

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What will be the best choice in terms of performance, 8Gb single rank or dual rank kit for E5-2600? All other parameters are identical.  One DpC, two DpC.

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Serge had some answers:

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We are basically in a transition period as 2Gbit DRAM approach end of life in the next 1-2 years and 4Gbit DRAM have become mainstream.

1. In a one DIMM-per-channel configuration, dual-rank will perform better than single-rank.  In most cases, only memory-intensive applications will notice the difference (like HPC).
2. In a two DIMM-per-channel configuration, the performance of single and dual-rank will be almost identical (within the accuracy of the measurement).
3. The single-rank DIMM will be lower power than the dual-rank DIMM.
4. Long-term, the single-rank DIMM will end up being lower cost and having better availability than the dual-rank DIMM.

The main reason we still have the dual-rank DIMM is #1, but I would not recommend it unless the customer’s application requires only one DIMM per channel and is memory intensive.

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