Ok to put DDR2-800 memory on a DDR2-400 mobo?

By tgreaves
Jan 23, 2008
  1. Im throwing together a machine for my GF.. I have a processor but need to get a socket 478 mobo.. The one I was looking at uses DDR2-400 memory and I have some DDR2-800 memory sticks laying around..

    Will it work ok to use the DDR2-800 sticks on a mobo that accepts DDR2-400 memory?
  2. dgower2

    dgower2 TS Maniac Posts: 238

    "Typically" you can run faster memory in a machine rated for slower memory - the memory simply runs ate the mobo spec. That said, memory issues are always subjective to the varying tolerances of the memory itself and the motherboard.

    I just combined 333 and 266 rated memory in a laptop that's spec'd at 266 - it flies with no issues.

    I think you'll have no problems.

    Just make double-sure that all the other specs are identical such as voltage, both unbuffered, both unregistered, same latency/speed specs e.g. 2-5-5-5, hopefully both with or both without SPD (or maybe all memory come with an SPD these days?).

    Try to run it with the memory, it won't cause any damage. If you start getting errors/crashes, you know it doesn't work.
  3. tgreaves

    tgreaves TS Rookie Topic Starter Posts: 40

    Good point.. Didnt think of the other specs..

    In case anyone is just dying of bordem and wants to check this out..

    This is the motherboard that the memory came out of.. Its an ASUS P5B premium vista..

    And this is the mobo that its going into, its a Biostar P4M900-M4..

    If nobody is in the mood to check ill do it sometime today..

    Its amazing how hard it is to find socket 478 stuff(mobo's, cpu coolers, ect)..

    Funny story, my friend works at the local landfill and brought home a computer that was being thrown away so he could use the power supply fan for another project.. It was a 4U rackmount case and he said that I could have it since he took the fan that he needed.. And what did it have....A p4 2.4 cpu that I had tested at work and found to work perfectly..

    The mobo that was in the rackmount case had snow on it so I figured it would be better to not use it and just buy another mobo.. ;)
  4. Mictlantecuhtli

    Mictlantecuhtli TS Evangelist Posts: 4,345   +11

    According to Biostar's site, that board supports DDR2 533/667 MHz RAM, so I guess your 800 will work at 667.
  5. Tedster

    Tedster Techspot old timer..... Posts: 6,000   +15

    please read the upgrading ram guide in the guides forum
  6. Harley2

    Harley2 TS Rookie

    It will run the ram at the fastest speed the mobo can handle. It will basically downgrade the ram, it'll work
    good luck.
  7. tgreaves

    tgreaves TS Rookie Topic Starter Posts: 40

    Its in and working great.. Thanks everyone for your help..
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