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Mixing PC2100 & PC2700 DDR sticks

Discussion in 'Overclocking' started by Swoggy, Dec 11, 2004.

  1. Swoggy

    Swoggy Guest

    After upgrading my memory my system has now become unstable could the
    fact that I purchased pc2700 ddr to go with my pc2100 ddr be causing it?

    On my kt266a board I've had it O/C to a FSB of 150 giving me 2000mhz
    from my Duron 1800 and by adjusting the pc2100 settings the mem runs stable.
    So when I came to get more mem I decided to get pc2700 as it would be
    useful next time I upgrade the board and would be able to take the 150
    FSB without running overclocked.
    Running everything at the same settings as before I now get programs
    warning me they need to shut down, I can then restart them but this
    happens about every 1/2 hr.

    Has anyone experienced this problem or got a solution.

    Thanks, Swog.
    Swoggy, Dec 11, 2004
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  2. Swoggy

    YanquiDawg Guest

    Could be. PC2100 is tested for 133(266) FSB. PC 2700 is tested for
    166(333)FSB. Not all PC2700 can run stabley at 150(300) FSB.
    Your BIOS may be settingall of your ram at PC2700 specs if you have that in
    the first slot and have the BIOS memory settings to default or by spd.
    Try changing the memory settings to CAS 3 to start with.
    YanquiDawg, Dec 11, 2004
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  3. Swoggy

    Tod Guest

    I agree, put the slow memory in first slot.
    Also, could the newer PC2700 be defective,
    try running with just the PC2700 only.
    Tod, Dec 11, 2004
  4. Swoggy

    Swoggy Guest

    I only get two options in the BIOS, 2 & 2.5 unstable with both.

    At the moment I'm running the PC2700 on its own at 150fsb to test it, no
    probs in 12hrs.
    So it seems they can both run stable at 150fsb individually, just need
    them to make friends.They're both Crucial brand the older PC2100 has
    chips on both sides while the newer PC2700 only on one side of the stick
    - any relevance ?
    Swoggy, Dec 12, 2004
  5. Swoggy

    John Smithe Guest

    You should check your motherboard documentation to determine if there are
    any restrictions with regard to mixing memory sticks with 'chips on both
    sides' and 'only on one side'. Look for references to 'double sided',
    'single sided', 'dual bank', 'double bank', 'low density' and 'high
    desnity' to see if any restrictions are placed on the use of memory sticks
    with these characteristics.

    You may want to try setting your system back to normal operating spec's
    and start from there. By adding a new stick of ram you have changed your
    system in a way that has altered its ability to overclock . For example,
    you have increased the loading on the memory bus by connecting more chips
    to the bus. You have also increased the electrical load on the power
    supply to the memory sticks. Try restoring the system to standard
    operating spec's. Then, if both memory sticks work together, try to
    overclock from there. In other words, redo your overclocking from scratch.

    You need to make sure that the operating conditions are compatible with
    the slower memory stick when both sticks are installed.

    1. Determine what operating conditions are compatible with the PC2100
    stick. Check the manufacturers website for the spec's for the PC2100
    stick. Look for numbers like CAS Latency, RAS to CAS Delay, RAS Precharge,
    Cycle Time, and Command Rate. There will usually be a 'Datasheet'
    available with these spec's on it. Use some software like CPU-Z or Everest
    to verify the actual operating conditions being set by the BIOS.

    Get CPU-Z from CPUID:

    Get Everest from Lavalys:

    2. Force all these settings in the BIOS to values that the PC2100 memory
    can operate correctly at. Don't use any 'automatic memory configuration' to
    ensure that what you select is used when your PC is running.

    3. Test these settings by running the the PC2100 memory to determine that
    it functions normally and stably.

    4. Test these settings again by running the the PC2700 memory to determine
    that it functions normally and stably.

    5. When both run normally and stably when installed individually, try them

    Keep in mind that you may no longer be able to overclock to the same
    extent that you did presviously, if at all.

    Some background info:


    Good Luck
    John Smithe, Dec 13, 2004
  6. Big <Snip>
    The answer is simple, and everyone's missed it.
    You had said kt266a
    I would have to guess it's max ram speed is also 266 MHz
    Just like it's cpu support.
    AMD is so much more simple in this way, a 333 MHz board can most
    times take up to DDR333.
    More on this after the, this is what Motherboard I'm using.

    This means that 333 is already pushing it close to being unstable
    and normal speed.
    I would say, get a new board.
    Asus "A7N8X" r nice, they still overclock well, but without
    spending the extra $$ for more bells and whistles.
    I believe you can get one for under 100$
    If you can take the ram back, I would try to get a new board.
    This is for a refurbished, OEM.. That means it comes with nothing. 42$


    Next one is for a full new one, only 72$

    as a matter a fact, all the "A7N8X" Boards r under 100$

    This is what I'm using for my AMD board @ the time.
    I have 1Gb in it.

    2xPC2100 & 2xPC2700
    I have put PC3200 in my Asus A7N8X board, but if I try to run it
    @ (DDR400) PC3200 Speeds, windows won't load.
    If I set it by SPD of which matches my 2200+'s bus, it's fine.
    I can get PC2700 running @ max, and stable, but for the CPU I'm using,
    That's probably pushing it a tad.

    Any way...

    Good Luck... Denny. ;-) :) Always with a smile, etc
    etc etc.. What ever.
    dennis e strausser jr, Dec 15, 2004
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