Revisiting DDR5-6400 vs. MRDIMM-8800 Performance With Intel Xeon 6 "Granite Rapids"
In the synthetic memory benchmarks, of course, MRDIMM-8000 shows off its hefty raw bandwidth advantages over DDR5-6400 memory on this Intel Xeon 6980P server.
When taking the geometric mean of 75 benchmarks with a mix of different workloads, the MRDIMM-8800 memory came out to being around 8% faster overall. But in areas where MRDIMM's memory bandwidth is much more valuable like HPC and AI workloads, they were typically well above that threshold. With HPCG for example showing around a 24% improvement and a number of the generative AI workloads hitting at least 10% improvements over DDR5-6400 memory.
When looking at the total server power consumption for this air-cooled 2U Giga Computing platform with one Intel Xeon 6980P and twelve DIMMs plus one NVMe SSD, we now have a better idea for the power consumption impact of using MRDIMMs. The total server power consumption reported by the BMC had a 619 Watt average with DDR5-6400 memory but that went up to a 712 Watt average with MRDIMMs, or roughly 7~8 Watt increase per memory module going from DDR5-6400 to MRDIMM-8800. But in the most demanding memory intensive applications the power increase was more significant: looking at the peak power consumption reported by the BMC went from 1014 Watts with DDR5-6400 memory to 1288 Watts with MRDIMM-8800 installed.
Quantifying the power impact of MRDIMMs was one of my personal takeaways from this revisiting of the MRDIMM-8800 memory performance.
MRDIMMs did operate slightly warmer than DDR5-6400 ECC server memory. With the BMC reported DIMM_6 temperature, the Micron MRDIMM-8800 modules tested were around 5 degrees Celsius warmer than Micron DDR5-6400 server memory modules.
That's the fresh look at the MRDIMM-8800 memory performance available with Intel Xeon 6 Granite Rapids. Thanks to Intel for supplying the original Xeon 6980P and memory review samples and then Giga Computing supplying their new R284-A92-AAL1 server to make this testing possible. In case you missed the article earlier this week, on a related note also check out Intel Xeon 6980P "Granite Rapids" Linux Performance One Year Later.
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