DDR266 and P4: what speed does the RAM run at?

Well, that's basically the question: if you use DDR266 RAM with a P4 CPU and a 400MHz P4 motherboard; will the ram then run at 100MHz, (with the double bandwidth making it 200MHz)?
If this is the case, wouldn't an Athlon CPU running at a comparable CPU-clock and on an Athlon-ready motherboard have a 33% speed advantage on the FSB, thus being the faster system?
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  1. heh no yes no

    well ddr266 is 133mhz ddr266. and you still get the 400mhz FSB, but the memory will only operate at 266mhz.

    Quote:
    If this is the case, wouldn't an Athlon CPU running at a comparable CPU-clock and on an Athlon-ready motherboard have a 33% speed advantage on the FSB, thus being the faster system?

    no


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  2. Download and read the data sheet here.

    <A HREF="http://www.intel.com/design/chipsets/datashts/290725.htm" target="_new">http://www.intel.com/design/chipsets/datashts/290725.htm</A>

    Everyone argues about the clock frequencies of the 845 chipset but they are clearly stated in the 845 MCH data sheet.

    System Bus 400MHz
    Memory Bus 133MHz
    AGP Bus 66MHz
    PCI Bus 33MHz


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  3. The 845 Chipset works with PC133, DDR200 and DDR266 RAM.
    It does not support PC100.
    If DDR200 is used the memory bus will sync at 100MHz.

    <font color=red><i>Doctor Hooter</i></font color=red> <A HREF="http://www.page3.com/" target="_new"><b>(·Y·)</b></A>
  4. ok guys, thanks for your answers.
    while we're on the topic: the PCI bus. i have a pci ethernet card running on a 10MB/s ethernet (the card is 10/100). does the speed of the PCI bus in any way limit the speed of the network?
  5. The chipset <i>decouples</i> the FSB and memory, so basically its all bandwidth game. The memory, whatever kind must get the chipset the highest possible bandwidth, which is passed on to the processor on its native bus. So a single channel 133 MHz DDR memory working 2.1 GB/sec can easily be coupled with the P4 native double channel double pumped 100 MHz bus, as the other busses.

    girish

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