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B550I AORUS PRO AX - A couple of simple questions

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  • B550I AORUS PRO AX - A couple of simple questions

    Hello everyone, I just jumped on the Ryzen train I got a couple of questions:

    - Despite setting 100mhz Bus Clock in bios, HW and AIDA reports 99.8mhz. So my memory clock is 1896.5 at 38x; not precisely synced with IF set at 1900mhz. Is this normal ?
    - Despite disabling both GearDown settings in bios, Tcas/Trcd/Trp set at 15/15/15 in bios will run at 16/15/15. Am I missing something ?
    - I red Vsoc, VDDP and VDDG voltages are the ones to look after if I want to try my luck past IF@1900mhz. Is there something else ? What would be the baseline you would recommend to safely experiment with those ?

    Thanks !

    Specs:
    B550I AORUS PRO AX (rev. 1.0) - BIOS F11 (2‎020/12/31)
    Ryzen 5900x
    G.Skill Ripjaws F4-4000C17D-32GVKB 2x16GB / DR - CL17-18-18-38 @1.40V

  • #2
    - Disable Spread spectrum, than your base clock will run at 99,98 MHz.
    - Ryzen cpu's don't like ueven CAS latencies, so that may be the reason why it run at 16.
    - I can't boot with IF 1900 MHz, but I can boot at 1933 and higher (to 2000 MHz).

    Comment


    • #3
      Thanks for you answers ! I'll go check that asap.

      Also does anyone knows when PBO 2 is coming on this board ?

      Comment


      • #4
        You're welcome!

        Maybe a beta BIOS based on Agesa 1.1.9.0 will come this week, PBO2 is part of it.

        Comment


        • #5
          - I have this board and with GDM off I can boot in CAS 15 (and is reported as CAS 15 in Windows RAM programs like ZenTimings and DRAM Calculator). It is also not true Ryzen doesn't like odd CAS latency instead of even. I believe this was true in first gen Ryzen but no problem now.
          So I'm not sure why yours won't stay at 15

          - I also have this weird bus clock freq. Not sure if it's normal or not..

          - it's my understanding those are the voltages you want to modify for IF OC. But I am also unable to boot past 1867 (1900 no post, haven't tried higher). You can go up to 1.1 VDDP and VDDG (but this is higher-safe end) and up to 1.3 vsoc. But it's balacing act because too high can cause errors too. So you can try playing in those ranges. It is totally safe to use 1.1 and 1.3, and definitely safe for testing. But it seems not benefit to go higher than these values for 2000 IF because I saw many reports of 2000 IF with values slightly less than these voltages

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          • #6
            Yeah my ram won't CAS 15 no matter what. Tried 14 but no post.
            Disabling Spread Spectrum really helped. I'm not sure about real life benefits though, but now it's synced much more tightly.
            Thanks for those baselines. Infinity fabric stuff seems to get into very positive developments with latest beta bios including agesa 1.2.0.0, check them.

            Comment


            • #7
              What did disabling spread spectrum do for you? Not sure what you mean by synced more tightly. Do you mean it allowed you to lower secondary timings further, or something else? Oh, or maybe the bus clock is now at 100mhz?

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              • #8
                Memory Bus, as reported by AIDA, is now synced or at most 0.2 mhz away from 1900mhz.

                I realized I can now set CAS 15 with latest bios contrary to what I said.

                Overall the best timing improvement I was able to achieve is tRFC / 2-4. Those values don't run at XMP on auto, you might wanna set manually.

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