Memory configuration for dual CPU T7500

Discussion in 'Dell' started by Guest, Oct 7, 2010.

  1. Guest

    Guest Guest

    I am a bit confused by the documentation for my new T7500.


    ====beg quote====
    Dual CPU configurations (6 DIMM slots on MB plus 6 DIMM slots on Riser)

    * If configuration contains DIMMs of all the same size, populate in
    the following order: MB_DIMM1, Riser_DIMM1, MB_DIMM2, Riser_DIMM2,
    MB_DIMM3, Riser_DIMM3, MB_DIMM4, Riser_DIMM4, MB_DIMM5,
    Riser_DIMM5, MB_DIMM6, Riser_DIMM6.
    * If configuration contains DIMMs of mixed sizes, populate the
    larger DIMMs in the dual-processor riser.

    =====end quote=======

    I got my system with 2gig installed(two rdimms), presumably in:

    MB_DIMM1 and Riser_DIMM1

    I am adding two 4gig Crucial rdimms.

    Should I put both in the riser as the 2nd point seems to indicate?
    Or 4 in MB1, 1 in MB2 and 4 in R1 and 1 in R2?

    Some of the wording on the documentation seems to indicate that the
    MB memory is for CPU1 and Riser memory is for CPU2 (both are quad cores,
    but that probably does not matter).

    Thanks in advance,
    Guest, Oct 7, 2010
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  2. Guest

    me Guest


    Congrats on your new behemoth, I'm sure you'll enjoy it. Glad to see all
    the caddies came too ;-))

    I had a similar dilemma and came to the conclusion that if the DIMMs are of
    unequal size, then the largest should go on the riser card. But I cheated
    and bought 3 larger, but equal sized DIMMS and replaced them in the slots
    that were already populated. I will put the smaller ones back in at some
    point so I anticipate putting the smaller ones on the MB and the larger ones
    on the riser card.

    Mine was originally populated with Hynix memory, so I did a search on
    Crucial for some of a greater capacity but same spec, i.e. same CAS, ECC,
    Buffered and same speed. They work fine so far!

    A word of caution if/when taking out the riser card - although it comes out
    easily, be sure you reconnect everything when you replace it (on board fan
    connector and MB connector I think I removed, but it's in the manual). It's
    easy to forget one!


    me, Oct 8, 2010
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  3. Guest

    Guest Guest

    So you do have to remove the riser to get to the mb dimm slots?

    I have not opened it again since my first quick look. One way I
    thought of cheating was to pull the 1gb from the riser, and put
    both 4gb there, that way I do not need to get to the mb dimm slots
    and I would have 9 rather than 10gb which will probably be enough.

    I am going to do it in an hour or so.

    Thanks for all your help,
    Guest, Oct 8, 2010
  4. Guest

    me Guest

    I believe you can get access to the MB memory slots without having to
    remover the riser card. You will need to remove the riser card to put
    memory on it, so I think your plan will work. Plus you should be able to
    put the one you removed from the riser into the MB slot 2. As it's DDR3
    memory, there are three channels you need to populate first (i.e. slot 1,2,3
    before going onto 4,5,6, see manual for layout) and you would end up with
    two 1Gb DIMMs on the MB and two 4 Gb DIMMs on the riser, each in their
    respective slot1 and slot 2. I feel that should work, but obviously your



    I think
    me, Oct 8, 2010
  5. Guest

    Guest Guest

    So the whole riser assembly, with CPU, fan and memory slots?

    I could not get the shroud off the MB memory with the riser in
    there. It will not lift up, so I need to pull the riser assembly

    This is a trickier job than I have done before.

    Attn Ben Meyers: Do you ever work inside 128? I might
    chicken out of this one.
    Also I did not see any PCIe power cables. The cheap video card I got
    for it is powered by the mother board. I will need to get some
    converters to get power from the other connections. More research
    to be done.
    Guest, Oct 9, 2010
  6. Guest

    Guest Guest

    I did not chicken out, and getting to both memory banks were far
    easier than it looked to me at first.

    But the first time I did it I got a bios message that my memory
    had changed, and was in non-optimal slots. I let it go ahead to
    windows, and windows saw the full 10gb.

    I reread the documentation and realized that it was a bit misleading.
    They label the physical riser dimm slots in order, from 1 to 6. They
    are really 1-4-2-5-3-6.

    So I opened the case again, and put the two 1gb rdimms in slots 1 and 2
    (with an empty slot in between). I did the same with the two 4gb rdimms
    on the riser. I triple checked the slot numbers on the memory slots.

    No boot. The post was stuck toggling between two sets of lights, one
    indicating PCI configuration was going on, and another saying that
    memory was not working properly.

    Opened again, reseated all four RDIMMS very carefully, checked all power
    connections, reseated the video card. No help.

    On the fourth try I put it back into the original configuration. With
    one 1gb in mb slot 1 and 1gb in riser slot 1. Posted and the bios
    reported a checkpoint at Ithr, whatever that means.

    I will contact support and google. Barring an obvious error on my part,
    I will try it with the 4gb rdimms in the first slots and see if I get
    good boots with 8gb. But that is for tomorrow...

    I wonder if one of the Slot 2s is bad somehow.

    I think I will run memtest on the current 2gb.
    I will have to delay thinking about this until I fix the rest...
    Guest, Oct 9, 2010
  7. Guest

    me Guest

    Yes, the whole riser does come out quite easily. Once you have done it you
    can appreciate the design and engineering applied to it ;-))
    Sorry I should have mentioned there is a shroud over the MB CPU and DIMM
    area that does need to be removed first. This seems to channel the flow of
    air from the front fan. On mine, it just pulls off with careful pressure
    (some at the front fan end to release it there). It does feel reluctant,
    but I've taken mine off several times now without incident. I do think you
    need to remove thiis before removing the riser card as there is a connector
    on the side of the riser that this covers whilst in situ.

    The riser assembly then comes out real easy, once you open the handle and
    pull. It is a "quick release" type of mechanism that actually pushes the
    riser away from the MB, This also protects the two multiway connectors that
    attach to the MB when you re-insert as it doesn't need much force to
    replace. I had my case on its side and gravity does the trick.
    Hey, please don't chicken! Seriously though, it is your call and I respect
    that, but I'm happy to try and help as necessary. I felt nervous the first
    time it did this but it is designed to come apart as per the manual.
    In fact the first time I took the side panel off, I noticed that the light
    on the network adapter was still flashing. and I realised the PSU has a
    hefty storage capacity, so when you want to work inside the case either wait
    a few minutes after switch off, or pull out the mains from the rear of the
    case and then do a switch on to discharge it. Better safe than sorry!
    These comments are not aimed to worry you - just re-assure you and pass on
    safety awareness. I'm assuming you have worked on other computers and added
    extra bits. This is no different, just bigger and better!
    I haven't looked for extra cables to supply power to video cards as the PCIe
    bus seems able to power two separate PCIe x16 video cards, along with the
    other slots. Anyway, there should be power to spare as it is an 1100 watt
    psu!. I guess you could use an adapter on one of the spare power leads from
    any unused front 5.5 inch bays.

    I'm off to bed now, but happy to chat further over the weekend if you wish.
    Take care and see you further down the group.

    me, Oct 9, 2010
  8. Guest

    Guest Guest

    Yes, it was impressive. It looked really daunting at first, but was
    a snap.
    I thought I needed to get the whole riser out first.
    Anyway as I need to take out the riser anyway, I do that
    It is a really slick design.
    That is how I feel now, but I wish I knew why it was not working.

    I just tried to boot to memtest3.4a, but the T7500 does not like it.
    It goes through the controller bios, then regular bios, then started
    to start memtest, then goes back to the Dell splash and starts over.

    That is what I will need. They make them. There are a lot of spare
    power cables, just none that fit my cards.
    Yes, you are up late, if you are in England as I have gathered.

    Thanks a lot!

    Guest, Oct 9, 2010
  9. Guest

    me Guest

    I thought I'd check back before I switched the monitors off, just in case!

    I used the in-built bios mem test after boot and pressing F12 I think?
    Anyway, if you do that and select the extended test it runs for 30 or 40
    mins doing various "walk" tests and other stuff with the memory. After
    that, I let Windows boot and checked it saw all the memory under task
    manager. I surely hope she boots for you ok. Are all the connectors back
    and secure on the riser? If normal boot doesn't complete, the flashing
    lights on the front are a diagnostic to indicate how far the boot process
    has got. Information on what they mean is in the manual under diagnostics.
    One thing I know is that if she doesn't want to boot, you can remove the
    riser card and boot with just one CPU. I have done it and it works. Then
    you can put the memory on the MB and test it if need be.
    Well it's 03:30 here and I must bail - sorry. I'll catch up later and hope
    all is well.

    Goodnight from Gloucestershire, England.
    me, Oct 9, 2010
  10. Guest

    me Guest

    Hi Tim.

    The T7500 can take two CPU's, one on the MB and one on what is called a
    "riser" card. It is a daugherboard that attaches to the MB via two multiway
    connectors and effectively sticks out at right angles to it. If you think
    of the case being placed vertically, then the MB is also vertical and the
    riser card is a short board attached to it horisontally. It carries the
    additional CPU, memory and support chips.
    I'm not sure if the T3500 has one, but if you download the service manual
    from Dell support you'll probably see. In fact, I'd recomend you download
    this anyway as it is very useful and doesn't come with the PC.


    me, Oct 9, 2010
  11. Guest

    Guest Guest

    Yes, everything was well placed.

    It just did not like the following (physical layout):

    dimmm slot # 1 4 2 5 3 6
    mb mem(gb) 1 0 1 0 0 0
    ri mem(gb) 4 0 4 0 0 0

    It did boot, with a bios warning about non-optimal dimm population
    in the following layout.

    dimmm slot # 1 4 2 5 3 6
    mb mem(gb) 1 1 0 0 0 0
    ri mem(gb) 4 4 0 0 0 0

    I have a question into tech support. Meanwhile I have fully tested
    the two 1gb rdimms with memtest86+ v4.1, and will shortly pull that
    memory and try with the two 4gb rdimms in slots 1.
    Yes, that is very late! I lived two years when a kid in Thaxted,
    Essex. My uncle was an expat in England for most of his life, so
    we went over a lot to visit him and his family. The last time I
    was there was 1.5 days in 07 for his funeral. I have very fond
    feelings for England. I still love old English junk food (bangers,
    fish and chips...)

    Thanks again,
    Guest, Oct 9, 2010
  12. Guest

    me Guest


    That's a very good observation you have there and I would be interested in
    the reply from tech support. What you describe does seem at odds with the
    guidance words from the service manual you quoted to start with. I've
    re-read the guidance several times and your first configuration seems
    correct to me. Hopefully all will become clear soon...
    Nice to hear your Uncle settled over here and that you have a soft spot for
    England. Essex is the SE of the country and I'm more towards the SW.
    Unfortunately that big place called London is on the way to Essex from here
    and I try to avoid going there if I can!


    me, Oct 9, 2010
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