Reply to post: Article misses a factor of 2 on memory BW

AMD does an Italian job on Intel, unveils 32-core, 64-thread 'Naples' CPU

DrBandwidth

Article misses a factor of 2 on memory BW

The article states: "Also "Naples" supports up to 21.3GBps per channel with DDR4-2667 x 8 channels (total 170.7GBps), versus the E5-2699A v4 processor's implied 140GBps."

This is based on a faulty interpretation of the statement that the AMD processor has "122% more memory bandwidth". The author apparently interpreted this as 1.22x as much memory bandwidth, to compute 170.7GB/s/1.22 = 140 GB/s. The correct interpretation of "122% more" is "2.22x", yielding 170.7 GB/s vs 76.8 GB/s. This implies 4 channels of DDR4-2400 on each socket of the Xeon E5-2699 v4, which is consistent with Intel's published specifications. The use of "1866 MHz" for the Xeon E5-2699A v4 in an earlier slide may be correct for a configuration with multiple DIMMs per channel -- the details vary by product and are not easy to look up.

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