Fast DDR4 RAM options

[Harmony]

What RAM would you guys put in the following system

MZ32-AR0
EPYC 7643

I bought a few SKhynix 64GB 2Rx4 PC4-2933Y-R83-12 HMAA8GR7MJR4N-WM the performance isn't that much better than the Micron 32GB PC4-2400T-R RDIMM MTA36ASF4G72PZ-2G3 I had

sysbench --test=memory --memory-block-size=4G --memory-total-size=32G run

32768.00 MiB transferred (12839.80 MiB/sec)


General statistics:
    total time:                          2.5504s
    total number of events:              8

Latency (ms):
         min:                                  316.78
         avg:                                  318.78
         max:                                  320.81
         95th percentile:                      320.17
         sum:                                 2550.21

Threads fairness:
    events (avg/stddev):           8.0000/0.00
    execution time (avg/stddev):   2.5502/0.00

What RAM reached 20,000+ Mib/Sec

Also tried SAMSUNG 64GB 2RX4 PC4-3200AA-R (3200MHz) ECC MEMORY MODULE - M393A8G40BB4-CWEGY which seems to be slightly worse than MTA36ASF4G72PZ-2G3

 

[rtech]

How many of them do you have? EPYC likes all 8 RAM channels used.
Can you verify on which frequency RAM runs?

 

[Harmony]

How many of them do you have? EPYC likes all 8 DIMM slots filled up.
Can you verify on which frequency RAM runs?

I don't have 8 3200 so I can't confirm that. Speed difference with 4/8 2400/2933 is not much.

They show correct frequency.

 

[rtech]

sysbench --test=memory --memory-block-size=4G --memory-total-size=32G run

Total operations: 8 (    2.08 per second)

32768.00 MiB transferred (8523.71 MiB/sec)


General statistics:
    total time:                          3.8425s
    total number of events:              8

Latency (ms):
         min:                                  479.39
         avg:                                  480.29
         max:                                  480.92
         95th percentile:                      484.44
         sum:                                 3842.33

Threads fairness:
    events (avg/stddev):           8.0000/0.00
    execution time (avg/stddev):   3.8423/0.00

Well you are better than old Xeon E5-2680 V2 using DDR3. What would be your ideal numbers? Consumer stuff is faster?

 

[Harmony]

Probably closer to this. I have a ASRock X570D4U Ryzen 5950X running 4x M391A4G43AB1-CWE Samsung 32GB DDR4 PC4-25600 3200MHz (clocked down to 2666)

32768.00 MiB transferred (15221.04 MiB/sec)


General statistics:
    total time:                          2.1523s
    total number of events:              8

Latency (ms):
         min:                                  267.61
         avg:                                  269.02
         max:                                  271.90
         95th percentile:                      272.27
         sum:                                 2152.16

Threads fairness:
    events (avg/stddev):           8.0000/0.00
    execution time (avg/stddev):   2.1522/0.00

 

[rtech]

On AMD web page there are tuning guides maybe you could look at them?

https://www.amd.com/en/processors/tuning-guides-server