1. Great post Steve, I have had the same warning, and had just assumed it to be overzealous warning logic in the BIOS. Thanks for publicising Dan’s answer, he is indeed The Man.

  2. Blissex

    it is a bit surprising to see this surprise about dual channel memory access and its requirements — I think that 2 channel memory setups have been around for 10 years (and now Intel have started using 3 channel memory systems too).
    Fortunately in many applications dual channel does not give a huge advantage, but it is nice to have. Fairly good details here:


  3. Ivan Costa

    Great post, but I am still confused. I had the same problem with my PowerEdge T105 with “1:512MB 2:412MB” (the factury config) and “3:2GB 4:2GB” (my additions). How can I do for solution this? How do you turned off the warning in every boot?
    Thanks a lot.


  4. Ivan:

    If I’m reading your post correctly, you currently have the DIMMs arranged like this:

    DIMM_1 (Channel 0): 512MB
    DIMM_2 (Channel 1): 512MB
    DIMM_3 (Channel 2): 2GB
    DIMM_4 (Channel 3): 2GB

    Notice how you’ve got each stick on its own channel – which means you’re sub-optimal. Arrange it like this:

    DIMM_1 (Channel 0): 2GB
    DIMM_2 (Channel 1): 512MB
    DIMM_5 (Channel 0): 2GB
    DIMM_6 (Channel 1): 512MB

    That way, you’ve got matching DIMMs using the same channel. You won’t get quad channel access to the memory (since all four sticks are not matched), but you should stop the warning since each channel has the same capacity. At least that’s how I’m understanding Dan’s email to me.

    Let me know if that change gets rid of the warning. Good luck!

    1. datapharmer

      Well I don’t think you are understanding Dan’s email. This configuration doesn’t work at all – your only option (that I have found is to have 4 matching DIMMs. Using 1,2, and 3,4 or 1,3 and 2,4 as recommended in the message yields the message or system halt, using 1,5 and 2,6 as you suggest also yields a system halt message. Moral of the story: go 1,2,3,4 and deal with the message or use DIMMs with matching sizes.


      1. Hey, DataPharmer. I haven’t tested non-matching sticks in those slots, so thanks for letting me know. I agree with you – the best solution is to use the same size DIMMs in every slot.


  5. Hi Steve –
    Thanks for the post. It took me lessthan a minute to fix my Dell 2970. No more error messages! I printed this off for my file of “don’t-forget-this” stuff.

  6. yogeshtyagi

    men config error massage appeir on frant panel

  7. Austin

    Poweredge T605

    Socket1 4 banks A1-A4
    Socket2 4 banks B1-B4

    The memory module sockets are divided into two equal branches (0 and 1). Each branch consists of two channels:

    Channel 0 and channel 1 are in branch 0.
    Channel 2 and channel 3 are in branch 1.

    Each channel consists of three memory module sockets:

    Channel 0 contains DIMM_1(A1)(4GB) and DIMM_5(B1)(4GB)
    Channel 1 contains DIMM_2(A2)(2GB) and DIMM_6(B2)(2GB)
    Channel 2 contains DIMM_3(A3)(4GB) and DIMM_7(B3)(4GB)
    Channel 3 contains DIMM_4(A4)(2GB) and DIMM_8(B4)(2GB)

    Am I not translating Dimm_# to A# or B# properly.

    From reading above I though this would be optimal and not give the error but it isn’t working.


    1. Austin

      Found this in the manual:

      Table 3-1. Memory Configurations

      24 GB configuration for dual socket

      DIMM A1-4GB DIMM B1-4GB
      DIMM A2-4GB DIMM B2-4GB
      DIMM A3-2GB DIMM B3-2GB
      DIMM A4-2GB DIMM B4-2GB

      Post shows 24 GB and at proper speed, but the message persists.

      Any advice?

  8. Rod

    I realize this post is old but I thought I’d chip in this. In a config where there are empty slots, why don’t you get the warning? If the first four have 2G and the last four are empty, by Dan’s own description, you aren’t optimal. So I don’t see how putting more memory in could possibly be any worse off. We have an R905 with 32 slots. I have 24 slots with 2G and 8 slots (last two on each bank) with 4G. Yes I get the message but when I was running without the 4G modules, I really wasn’t optimal either.


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