DDR400 & P4S533 Mobo

I just installed my Asus P4S533 Motherboard with a P4 2.26 Northwood chip. I also bought Samsung PC3200 Xtreme DDR400 memory.

Question: How do I know if my memory is running at DDR400?
I saw a BIOS setting "CPU/MEMORY FREQUENCY RATIO" and I have no idea what it does (the doc is CRAP)
When this is set to "AUTO" my computer won't post, so I set the ratio to 1:1 and it runs great.
Can anyone please help me understand:
Front Side Bus
Memory bus

As I understood it, my FSB is 133 and my CPU bus is 4 times that at 533. I have no idea how to determine the memory bus.

6 answers Last reply
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  1. right now, your memory is running at 133 mhz (266 ddr @ cpu:mem ratio 1:1).
    since your ram is rated at pc3200 (ddr400)...it should be able to do 4:6...
    anyways...lemme see if i can explain the mem ratios to you...
    the P4S533 has the following cpu:mem ratios:
    @ FSB < 133:
    1:1, 3:4, 3:5 and 3:6.

    @ FSB >= 133:
    1:1, 4:3, 4:5 and 4:6.

    since you have the P4 "B" with 133 FSB...ill talk about the cpu:mem ratios at 133 FSB (1:1, 4:3, 4:5, 4:6).
    consider this equation:
    CPU FSB / (CPU in CPU:MEMORY ratio) x (MEMORY in CPU:MEMORY ratio) = memory speed

    @ 1:1:
    133 / 1 x 1 = 133
    so your ram is running at 133mhz (266ddr).

    @ 4:3:
    133 / 4 x 3 ~ 100
    ram speed = 100mhz (200ddr)

    @ 4:5:
    133 / 4 x 5 ~ 166
    ram = 166mhz (333ddr)

    @ 4:6:
    133 / 4 x 6 ~ 200
    ram = 200mhz (400ddr)

    in your case, you should have your ratio at 4:6 because your ram is rated to run at that speed (ddr400)...if it cannot, then try a slower speed like 4:5...if your comp still wont post, then you may want to consider getting new ram...

    :eek: <b>Who fixed <font color=red>ATI</font color=red>'s leaky faucet??</b> :eek:
  2. Wow thanks pr497!!!
    That really helped me allot. I now have my memory running at 333Mhz, but can't get it to post at 400. Not sure what the problem is there, the memory should handle it.
    Anyway, I'm pretty happy with 333Mhz.
    Thanks again!

    Oh, can anyone recommend a good system spec display?
    I would like the SEE the 333Mhz for the memory.
    I looked around in Sandra and didn't see where it displayed the memory speed.

  3. Most mainboards aren't really "designed" to work with DDR400 so you may have to increase memory voltage in order to get it to work. Before you do this, however, I'd make sure you have a good power supply and definitely some RAM sinks to cool down your RAM as those things generate a lot of heat. Gone are the days when memory was only 5 degrees above room temperature.

    This little cathode light of mine, I'm gonna let it shine!
  4. Cool, thanks for the tip.
    What do you recommend as the top memory voltage before the risk outweighs the benefit?

    I am only running the stock HS & fan (ahh nice & quiet) so should I even attempt running my memory at 400 Mhz?

    Also what is the top safe temp for the CPU? My P4 2.26 got up to 114 F after about 1 hour of running Seti.

    Again, thanks for the advise!

  5. this is normal you didn't boot in auto with SPD memory configuration because your Samsung PC3200 Xtreme DDR400 memory is not supported by your motherboard.

    according to the mb specs. without overclocking:

    P4 2.26 FSB 133 / DDR333 supported.

    thus you have to set the correct parameters manually.

    the FSB must be 133Mhz. the correct ratio for DDR333 is 5/4.

    you can try an overclocking settings with the 6/4 ratio (then fitting the specs of your DDR400 memory) but you have to raise the DDR memory voltage before.

    <i> :smile: I like THG Interactive, Inc.</i>
  6. there is no pb with your temp at 45°C.

    CPU Bus 533Mhz
    Front Side Bus 133Mhz
    Memory bus 166Mhz (DDR333) 200Mhz (DDR400)

    <i> :smile: I like THG Interactive, Inc.</i>
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