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Memory latency confusion

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  • Memory latency confusion

    I recently upgraded from 3700X to 5800X (without swapping any other parts). I expected lower memory latency in PerformenceTest, but it seems way higher. I don't quite understand the number I'm seeing compared to the AIDA results which have lower latency as expected. Issues regarding how the memory calculation is extracted in PT? Technical issues with my config I haven't figured out yet..?

    Memory is stable at 1.35v in both scenarios. It complete 4x Memtest86 as well as extensive memory testing in Win10 without issues. As visible through listed frequencies in AIDA memory is in "coupled" mode. Memory timings identical for all tests.

    3700X results:
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    5800X results:
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  • #2
    The latency test uses an average of three tests that use a buffer size of 16KB, 64KB and 8MB so potentially the 5800x is doing badly in one of these tests which is dragging the average up.

    Looking at a handful of recent results for each CPU the 3700x has results from 31-48 and the 5800x is 39-55 (so your system is still reporting better numbers for both CPUs compared to what I saw), on average it does seems to perform slightly worse in the PerformanceTest latency test.

    We'll add some debugging to check if it's just one part of the test and get back to you with a new build.


    • #3
      Could you please launch this build in debug mode, run the latency test a few times and then email us the log files that are created.


      • #4

        Thanks for that, the results seem pretty consistent between the runs;

        Memory Latency: result: 39.177338 (result32K 21.562857 result64K 54.206169 result8MB 41.762989)
        Memory Latency: result: 39.316620 (result32K 21.471699 result64K 54.529732 result8MB 41.948425)
        Memory Latency: result: 39.588543 (result32K 21.850363 result64K 54.887363 result8MB 42.027901)
        Memory Latency: result: 39.986240 (result32K 21.647005 result64K 55.806976 result8MB 42.50473)
        Memory Latency: result: 39.275326 (result32K 21.387550 result64K 54.648949 result8MB 41.78947)

        Looking at the AIDA results they are probably running their test using a 64KB buffer, so the 3700X looks like it performed worse than the 5800X at this buffer size however in our test the 3700X performed better for one or two of the other buffer sizes