Supermicro H11DSi memory bandwidth

Feb 18, 2020
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Hello!

I have built a machine with 2 AMD Epyc 7282 CPUs on a Supermicro H11DSi board. It has 8 RAM slots per socket. I have 8 sticks of 16GB DDR4-3200 registered ECC memory, that is 4 sticks per socket.

The problem I'm having is - when the system is fully assembled multiple benchmarks show just 20 GB/s of memory bandwidth, while the bandwidth specified on AMD's website says 85.3 GB/s per socket. So technically i should be getting around 160 GB/s. I tried playing around with the BIOS settings and managed to reach 60 GB/s with only 1 CPU with all 8 RAM modules installed. What can I do to reach the memory bandwidth specified by AMD?
 

alex_stief

Active Member
May 31, 2016
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Which benchmarks? And which operating system?
Assuming you populated the DIMMs in a somewhat reasonable manner, the only way you will be seeing numbers close to the theoretical maximum is an AMD-optimized version of the stream benchmark. And you will need dual-rank DIMMs for it, one rank per channel takes a 10-15% hit to maximum memory bandwidth.