A7A266: Mixing memory sizes?

Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

My PC uses a A7A266 motherboard, which has two slots for DDR memory.
Currently it
has the following memory configuration:

512MB of memory (2 x 256MB) DDR SDRAM non-EEC 184 pin PC2100

The manual says:

"Install memory in any combination as follows".

Does this mean I can mix memory sizes? I'd like to replace one of the
memory sticks with a 512MB or 1GB stick, giving me either 768MB or
1280MB of memory, rather than having to replace both sticks.

Does this work? Has anyone else tried this configuration successfully?

Thanks,

P.
--
-pm

http://oceanclub.blogspot.com

"The sea was angry that day, my friends. Like an old man trying
to send back soup in a deli."
6 answers Last reply
More about a7a266 mixing memory sizes
  1. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    In article <d6ffqs$5mg$1@domitilla.aioe.org>, "Paul Moloney"
    <paul_moloney@hotmail.com> wrote:

    > My PC uses a A7A266 motherboard, which has two slots for DDR memory.
    > Currently it
    > has the following memory configuration:
    >
    > 512MB of memory (2 x 256MB) DDR SDRAM non-EEC 184 pin PC2100
    >
    > The manual says:
    >
    > "Install memory in any combination as follows".
    >
    > Does this mean I can mix memory sizes? I'd like to replace one of the
    > memory sticks with a 512MB or 1GB stick, giving me either 768MB or
    > 1280MB of memory, rather than having to replace both sticks.
    >
    > Does this work? Has anyone else tried this configuration successfully?
    >
    > Thanks,
    >
    > P.

    Yes, it means you can mix memory sizes. The important thing is
    to use all the same type of RAM. You probably know you cannot put
    SDRAM and DDR RAM in the board at the same time. The manual
    also mentions unbuffered and registered memory, and you cannot
    mix those types either.

    Have a look through Google, for comments about brand specific
    issues, or problems with the board in general. A couple of posters
    mentioned Micron chips didn't work well - but much has changed
    over the last four years, in terms of chip characteristics.
    (Different silicon die versions from every manufacturer...)

    The cheapest combo you could get, is a couple of 512MB sticks.
    At the 1GB size, there are the cheap "stacked" unbuffered 1GB
    DDR DIMMS, and the more expensive proper unbuffered 1GB DDR
    DIMMs based on 64Mx8 chips. The "stacked" ones place twice the
    loading of an ordinary module, on the memory bus - that means
    with a few exceptions, the memory controller will not be happy
    driving them. If you buy your 1GB DIMMs from a name brand source
    (Kingston, Crucial, CorsairMicro.com) chances are you'll get
    a proper module - the generic unbranded stuff is the stuff to
    watch out for.

    You could buy some 512MB PC3200 CAS3 memory, and it is backward
    compatible with PC2100. At PC2100 speeds, the memory will run
    at CAS2, which is as good as you can do. The reason I mention
    this, is PC3200 is much more common, and potentially cheaper
    than some old PC2100 that has been sitting on some vendor's
    shelf for a few years.

    Also, if you are using Win98, you know about 512MB being the
    largest totally trouble free memory size ? Between 512MB and
    1GB, you have to mod a file to make it work (didn't work
    stable for me until I dropped back to 512MB - it works
    for some people). Using more than 1GB on Win98 won't work.

    BTW - Does your AGP card work ? There was a poster "Dr Teeth"
    looking for help a few days ago. If your AGP slot is really
    working (texture transfer and all), perhaps you could give
    him a few words of advice.

    Paul
  2. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    "Paul" <nospam@needed.com> wrote in message
    news:nospam-1805051348000001@192.168.1.178...

    > Yes, it means you can mix memory sizes. The important thing is
    > to use all the same type of RAM. You probably know you cannot put
    > SDRAM and DDR RAM in the board at the same time.

    Yup, got that bit.

    > The manual
    > also mentions unbuffered and registered memory, and you cannot
    > mix those types either.

    Not sure which mine is; hopefully it's labelled on the module.

    > The cheapest combo you could get, is a couple of 512MB sticks.

    I was thinking of getting a 1GB module, and combining it
    with one of my existing 256MB module (ensuring that everything
    bar the size is compatible). Would 2 x 512MB be cheaper, or just
    an option that's more likely to be compatible?

    Cheers,

    P.
  3. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    In article <wYPie.8758$8K5.4181@newsfe3-win.ntli.net>, "Paul Moloney"
    <paul_moloney@hotmail.com> wrote:

    > "Paul" <nospam@needed.com> wrote in message
    > news:nospam-1805051348000001@192.168.1.178...
    >
    > > Yes, it means you can mix memory sizes. The important thing is
    > > to use all the same type of RAM. You probably know you cannot put
    > > SDRAM and DDR RAM in the board at the same time.
    >
    > Yup, got that bit.
    >
    > > The manual
    > > also mentions unbuffered and registered memory, and you cannot
    > > mix those types either.
    >
    > Not sure which mine is; hopefully it's labelled on the module.
    >
    > > The cheapest combo you could get, is a couple of 512MB sticks.
    >
    > I was thinking of getting a 1GB module, and combining it
    > with one of my existing 256MB module (ensuring that everything
    > bar the size is compatible). Would 2 x 512MB be cheaper, or just
    > an option that's more likely to be compatible?
    >
    > Cheers,
    >
    > P.

    To choose a name brand example:

    http://www.ec.kingston.com/ecom/configurator/modelsinfo.asp?SysID=10745&mfr=ASUS&model=A7A266+Motherboard&Sys=10745-ASUS-A7A266+Motherboard&distributor=0&submit1=Search

    1GB PC2100 CAS2.5 $107..$180 (four stores)
    512MB PC2100 CAS2.5 $ 48..$ 76 (five stores - one is OEM and warranty
    will differ)

    There is a Corsair Value Select 1GB for $90.
    http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=80098-34

    You'll notice on some of the descriptions on Pricewatch, that
    128Mx4 chips are used on some of these cheap ($57) 1GB modules.
    The $57 modules are not the ones I'd want to buy. The chips on a
    1GB module should be 64Mx8 chips (see if your vendor even knows
    how the modules are constructed - if there are heat spreaders
    on the modules, you may get some kind of story that they
    "don't know", which is not the right answer).

    http://www.pricewatch.com/prc.aspx?i=33&a=5025

    This is how a proper 1GB module is constructed. Sixteen chips
    of type 64Mx8, eight per side of module:

    http://www.valueram.com/datasheets/KVR266X64C25_1G.pdf

    If I was going to buy a 1GB module, I'd want the ability
    to return the module for a couple of 512MB modules, if
    the 1GB module doesn't work out (plus whatever the difference
    in price that exists on the day you do the swap). At these
    prices, a restocking fee wouldn't be too much of an issue.

    I guess my main reason for recommending 2x512MB is there is
    just less risk in the transaction. If you actually know a
    shop owner you trust, that may change the equation for you.
    I've been burned a couple of times buying generic RAM that
    went bad about a year later, so now I only buy name brand
    stuff (last two orders were Crucial). There aren't enough
    entries in Google, to make brand recommendations.

    Paul
  4. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    Paul wrote:
    [...]

    Phew! Thanks for all that, it's an education. :D Just one thing
    I missed earlier - is memory _always_ backwards
    compatiable? For example, is PC3200 compatiable with PC3000,
    PC2700 , PC2400 and PC2100? Or is it only compatible
    when explicitly stated?

    Cheers,

    P.
    --
    -pm

    http://oceanclub.blogspot.com

    "The sea was angry that day, my friends. Like an old man trying
    to send back soup in a deli."
  5. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    In article <d6sm05$bbl$1@domitilla.aioe.org>, "Paul Moloney"
    <paul_moloney@hotmail.com> wrote:

    > Paul wrote:
    > [...]
    >
    > Phew! Thanks for all that, it's an education. :D Just one thing
    > I missed earlier - is memory _always_ backwards
    > compatiable? For example, is PC3200 compatiable with PC3000,
    > PC2700 , PC2400 and PC2100? Or is it only compatible
    > when explicitly stated?
    >
    > Cheers,
    >
    > P.

    I have looked at the datasheets for the individual RAM chips,
    and the specified clock goes all the way down to handle PC1600
    rates. So, the answer is yes, they are backward compatible.
    Without any statement from the vendor. At least, I haven't found
    a datasheet yet that said otherwise.

    The only time it is necessary to buy a specific speed of RAM,
    is if you have a brain-dead BIOS design. There are some BIOS
    setup screens, that have absolutely no options for controlling
    memory. For some of those, you buy a PC2700 DIMM if you want to
    force such a stupid motherboard to run at DDR333. In other
    words, the SPD on the DIMM is used to "steer" the motherboard
    where you want it to go, as the motheboard is permanently in
    "Auto" mode. Which is a pretty pathetic way to do things, but
    necessary for some of the microATX boards.

    Paul
  6. Archived from groups: alt.comp.periphs.mainboard.asus (More info?)

    Paul wrote:
    > I have looked at the datasheets for the individual RAM chips,
    > and the specified clock goes all the way down to handle PC1600
    > rates. So, the answer is yes, they are backward compatible.

    Cheers; in the end, I went for the following:

    http://www.dabs.com/uk/channels/components/memoryandaccessories/productView.htm?quicklinx=30R1

    1GB 184Pin DIMM PC3200 DDR Non-Parity CL2.5 memory

    It's Kingston; judging from reviews is good quality and compatible
    with my motherboard. If it doesn't work out in a 1GB + 256MB configuration,
    I'l return it and go for 2 x 512MB. Ta for your help,

    --
    -pm

    http://oceanclub.blogspot.com

    "The sea was angry that day, my friends. Like an old man trying
    to send back soup in a deli."
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