High density RAM?

Discussion in 'Computer Information' started by Budgie, Dec 22, 2007.

  1. Budgie

    Budgie Guest

    I'm running a Compaq Presario 6000 with 256Mb of RAM - it's in need of more!

    Specification I have is 184-pin PC3200 DDR400 CL=3.0 Non-ECC.

    Looking a EBay adverts, some are for high-density RAM - will that work?
    What's the difference?
    --
    Budgie
    NB Reply to newsgroup. Email address will get you nowhere.
     
    Budgie, Dec 22, 2007
    #1
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  2. Budgie

    Robert Baer Guest

    Budgie wrote:
    > I'm running a Compaq Presario 6000 with 256Mb of RAM - it's in need of more!
    >
    > Specification I have is 184-pin PC3200 DDR400 CL=3.0 Non-ECC.
    >
    > Looking a EBay adverts, some are for high-density RAM - will that work?
    > What's the difference?

    Good greif!
    NEVER buy RAM, hard drives, etc via E-bay unless you do not care
    about the provenance and the quality, and get the junk at junk pricing.
    Check out PriceWatch.
     
    Robert Baer, Dec 22, 2007
    #2
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  3. Budgie

    Pen Guest

    Pen, Dec 22, 2007
    #3
  4. Budgie

    Paul Guest

    Budgie wrote:
    > I'm running a Compaq Presario 6000 with 256Mb of RAM - it's in need of more!
    >
    > Specification I have is 184-pin PC3200 DDR400 CL=3.0 Non-ECC.
    >
    > Looking a EBay adverts, some are for high-density RAM - will that work?
    > What's the difference?


    The high density RAM in question would probably be 1GB PC3200 DDR.

    A "normal density" stick consists of (16) 64Mx8 chips. That forms
    two ranks, with one rank per side of the DIMM. Memory arrays are
    64 bits wide, to match the width of the DIMM memory bus. Two chip
    select signals control the two ranks of memory. Each chip select
    has 8 loads on it. Address/command drivers see sixteen loads, so
    that part is normal.

    A "high density" 1GB stick consists of (16) 128Mx4 chips. That forms
    one rank, spanning both sides of the DIMM. It takes all 16 chips, to
    make the necessary 64 bit wide array in that case. It is unclear
    to me, how the chip select works. Logically, you'd expect one chip
    select to drive all sixteen chips. They could also use the two
    chip select signals, and have the signals wiggle exactly the same
    way, but that requires chipset support for that operating mode.

    In any case, the advert for the high density RAM product on Ebay,
    will have a list of chipsets that support that kind of memory.
    You'll notice Intel chipsets tend to be missing, and if you download
    an Intel datasheet, they'll tell you they support x8 and x16 chip
    types.

    If you buy that Ebay RAM, then it may not be portable between all
    of your computers. For example, with the two computers I own that
    are worth using, the high density product won't work in one of
    them (Intel) and in the other (Nvidia Nforce2), only half of
    the stick registers. That is because, I gather, the Nforce2 lacks
    enough address bits to drive the "128M" part of the chip. It
    can drive a "64M" row and column, but is one bit short for driving
    "128M".

    So I don't recommend buying 1GB DDR from Ebay. I'm unaware of any
    "tricks" for 512MB DDR, and any kind of DDR2 you want to buy is
    probably OK as of today.

    As the other posters suggest, stick with safe, branded memory. It
    will have a warranty. In the case of Crucial, all of the memory
    I bought from them is still working. They also have an excellent
    sales interface, and they are one of the few retailers I didn't
    have to phone and pester.

    If the memory industry was an honest one, and had some scruples,
    such caution would be unnecessary. But the chip factories are
    willing to sell untested or out of spec chips to any third
    party who cares to buy them. The third party is then tasked with
    testing them. A lot of the cheap memory you find, may be poorly
    tested, because with the small profit margin, the only thing they
    can cut back on is testing.

    The x4 chip type should really only be used on registered DIMMs,
    Because in that case, the register chips help drive the extra load,
    and the Northbridge doesn't have nearly as much load on it. Registered
    DIMMs are typically used on servers.

    HTH,
    Paul
     
    Paul, Dec 22, 2007
    #4
  5. Budgie

    Budgie Guest

    "Budgie" <> wrote in message
    news:Id3bj.15112$...
    >
    > Looking a EBay adverts, some are for high-density RAM - will that work?
    > What's the difference?
    > --


    Thanks all for the explanations and advice.

    I'll steer clear of EBay. Now there's also EBuyer. . .

    --
    Budgie
    NB Reply to newsgroup. Email address will get you nowhere.
     
    Budgie, Dec 22, 2007
    #5
  6. Budgie

    HLS Guest

    Buy it someplace where they are known for quality products and
    quality customer service.

    I bought my RAM for a similar Compaq HP machine at Fry's.
    It worked fine.

    Newegg is also a good place.

    If you are trying to run that computer with Windows Pissyvista, you
    will need at least about 2 gigs total.



    > I'll steer clear of EBay. Now there's also EBuyer. . .
     
    HLS, Dec 24, 2007
    #6
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