AI7 (865PE) - A closer look at the Northbridge. .

Discussion in 'Abit' started by Wayne Youngman, Jun 29, 2004.

  1. Hi,

    I just been spending some time getting my 3 month old AI7 tweaked up a bit
    and have finally added my SP-94 HS :).

    While I was at it I popped off the ABIT NB-HSF and was amazed to see how
    small the northbridge actually is (looks just like a Coppermine CPU). I
    don't think it has a IHS so its basically just a bare blue slug mounted on a
    green PCB. on the bottom of the stock NB-HSF there is a square piece of
    thin white foam with a small square hole cut out so that the NB-Slug can
    make contact with the heatsink. AT first I thought this piece of thin white
    foam was a kinda *shim* but on closer inspection I noticed that there are
    little chip components around the base of the northbridge and I wondered if
    the foam was to prevent contact (or Short!) between these little chips and
    the bottom of the NB-HSF. Ideally I want to lap the bottom of the NB-HSF
    but to do this I would have to tear-off the white foam thing. .

    Can I just ignore this or should I *re-mask* the area off with electricians
    tape after?

    Any comments?
    Wayne Youngman, Jun 29, 2004
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  2. Wayne Youngman

    frodo Guest

    I believe that thin white foam is the heat transfer device; not as good as
    the paste stuff, but cheaper and pre-applyed at the heat-sink factory to
    make OEM/end-user installation a no-brainer. Why it would have a cut-out
    where the NB chip goes is beyond me, unless the intent was for the NB chip
    to seat against the metal and allow the foam to get down closer to the
    small surface mount caps/resistors surrounding it.
    frodo, Jun 29, 2004
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  3. As, indeed, it should. Intel have been building their northbridges in a 0.13
    micron FC-BGA package for some time. That includes all the 8xx chipsets as
    well as all (IIRC) the 72xx server family.
    It is. Primary function is to make sure the heatsink is correctly aligned
    over the core.
    There may be an element of insulation to it, but that would be a secondary
    factor seeing as the anodising on the the heatsink has pretty good
    insulating properties. If you're going to lap that off of course there's a
    slightly different issue, but I think you'll find the discretes mounted on
    the topside of the substrate are lower than the top of the northbridge core
    Not a huge amount to gain as the northbridge runs pretty cool anyway.
    Provided you're certain that the spring aligns the heatsink correctly over
    the core, there's no desperate need to refit the foam. No desperate need to
    insulate the heatsink base either, but on the other hand doing so won't do
    any harm.

    Richard Hopkins
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    Richard Hopkins, Jun 29, 2004
  4. "Richard Hopkins" wrote

    Hi Richard,
    thanks for that reply, very informative. I didn't realise that anodising
    something made it less conductive. I will have to check the clearance issue
    again, but at first glance it looks like the *discretes* actually touch the
    base of the NB-HSF (they leave quite a dent in the white-foam-buffer!, so I
    figure they must be pressed up hard against it).

    Anyway I have left the foam on there and just cleaned off the
    pink-bubble-gum and replaced it with a dab of AS/Ceramique.

    I wonder if the 3rd Party NB-HSF's are anodised?.
    Wayne Youngman, Jun 29, 2004
  5. Wayne Youngman

    TomG Guest

    hmmm... I replaced my NB cooler and did not mount it up with any foam. not
    too sure you will really gain much lapping that heat sink but I'm sure it
    will help some.


    Thomas Geery
    Network+ certified Abit Mirror <----- Cable modem IP
    This IP is dynamic so it *could* change!...
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    TomG, Jun 29, 2004
  6. Wayne Youngman

    TomG Guest

    I believe it heated it's way through the foam as I saw the same thing when I
    replaced my NB cooler and just had to take the trouble to remove all of the
    foam before mounting up the new cooler.


    Thomas Geery
    Network+ certified Abit Mirror <----- Cable modem IP
    This IP is dynamic so it *could* change!...
    over 130,000 FTP users served!
    TomG, Jun 29, 2004
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