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DDR4 Memory Scaling & DDR4-3600 Testing With AMD Threadripper On Linux

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  • #11
    Originally posted by Kemosabe View Post
    Does this mean any 4x configuration > 2x?
    Within the confines of Threadripper, yes. This is not generalizable to anything that has less than 4 memory channels such as the normal Ryzen parts. You basically get a lot more bandwidth by filling channels than you do from increasing the frequency of a particular channel.

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    • #12
      Originally posted by coder111 View Post
      Hmm, it's a bit of a shame highest speed ECC memory I can find is DDR4-2666.

      I'd love to have ECC, but if does look like it would be a substantial hit on performance... And probably my wallet as well.
      Faster ECC sticks should start appearing Q12018. There are two chips currently missing to make it happen. One can be sampled, but only pre-ordered, the other should be available for sampling soon. I forget what they are called.

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      • #13
        Originally posted by coder111 View Post
        Hmm, it's a bit of a shame highest speed ECC memory I can find is DDR4-2666.

        I'd love to have ECC, but if does look like it would be a substantial hit on performance... And probably my wallet as well.
        ECC memory overclocks too and you can see exactly when you're going too far. On my FX-8350 I got 1866 with decent timing out of garden variety DDR3-1333 Kingston ValueRAM DIMMs, it just took some time to find the right settings.

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        • #14
          Originally posted by coder111 View Post
          Hmm, it's a bit of a shame highest speed ECC memory I can find is DDR4-2666.

          I'd love to have ECC, but if does look like it would be a substantial hit on performance... And probably my wallet as well.
          I have 2x 16 GiB DDR4-2400 ECC Memory @3200 MHz. The RAM clocks are really important for Zen CPUs. Not just for EPYC, the same counts for Threadripper and Ryzen.
          There are many benchmarks that draw a weak picture for Ryzen when it comes to gaming. But usually when you see which memory has been utilized you have the explanation for the weak performance.
          With the right memory clocks you have about the same performance per clock like Intel CPUs offer for a much lower price.

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          • #15
            Originally posted by coder111 View Post
            Hmm, it's a bit of a shame highest speed ECC memory I can find is DDR4-2666.

            I'd love to have ECC, but if does look like it would be a substantial hit on performance... And probably my wallet as well.
            You can still overclock ECC memory, its just motherboards don't typically allow you to because they are "server" motherboards. I actually literally just got my ryzen 1700x desktop computer to assemble into a computer right now and I have two sticks of 2666mhz 8gig (16 total) crucial ECC memory. I'm very tempted to try overclocking it. With overclocking ECC memory you can easily tell when there are issues (at least with linux).

            Think I should try overclocking my ram?

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            • #16
              Originally posted by Ehvis View Post
              "The memory timings were not tweaked between the different frequency levels."

              Can you clarify what that means? Because if it means that the timings were kept the same for tests, then the test would be a bit silly.
              G.SKILL 4 x 8GB TridentZ RGB F4-3200C16Q-32GTZR module kit has CAS-16 (16-18-18-38) timings at DDR4-3200
              G.SKILL 4 x 4GB Ripjaws V Series F4-3600C17Q-16GVK module kit has CAS-17 (17-18-18-38) timings at DDR4-3600
              and the Ripjaws has CAS-15 (15-16-16-32) @ 3200, CAS-13 (13-14-14-28) @ 2666, and CAS-11 (11-11-11-28) @ 2133

              If the timings were left the same between 3600 and 2133 then 35% of the potential performance of the memory was left on the table due to sheer laziness.

              It's quality benchmarking like this which sets Phoronix apart from other credible review sites, lol.

              It's also why I will never trust APU benchmarks from this site... because Michael refuses to disclose memory timings for the APU tests, even though I have suggested him how to easily automate that reporting.
              Last edited by linuxgeex; 11-25-2017, 02:07 AM.

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              • #17
                Can you please test Quartus compilation time with Threadreaper? We'r giing to buy workstation for compilation. I prefer AMD but not sure if it will outperform Xeon setup in price/performance.

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                • #18
                  Originally posted by tiwake View Post
                  Think I should try overclocking my ram?
                  No. If you need ECC ram, you need stability. Then I recommend using supported frequency and timing for the chips. If you want to overclock, you probably do not need ECC ram, in which case you can by ram rated to 3600MHz from factory. Overclocking is always a game of chance. Anybody telling you differently do not know what they are talking about.

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                  • #19
                    Originally posted by linuxgeex View Post

                    G.SKILL 4 x 8GB TridentZ RGB F4-3200C16Q-32GTZR module kit has CAS-16 (16-18-18-38) timings at DDR4-3200
                    G.SKILL 4 x 4GB Ripjaws V Series F4-3600C17Q-16GVK module kit has CAS-17 (17-18-18-38) timings at DDR4-3600
                    and the Ripjaws has CAS-15 (15-16-16-32) @ 3200, CAS-13 (13-14-14-28) @ 2666, and CAS-11 (11-11-11-28) @ 2133

                    If the timings were left the same between 3600 and 2133 then 35% of the potential performance of the memory was left on the table due to sheer laziness.
                    I have to agree - XMP profile + auto settings for secondary and tertiary subtimings on this platform are bad. Manual tight settings give both better bandwidth and lower latency.
                    And it is a pity Michael has only sh...y hynix based RAM for testing
                    This [email protected] with auto subtimings will be worse than properly tuned b-dies at 3200....

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                    • #20
                      Originally posted by tiwake View Post
                      Think I should try overclocking my ECC ram?

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