P4 Bus speed?

I was wondering if someone could explain P4's bus speed. I have a 2.4 533Mhz P4. I would like to over clock it but not sure where my FSB should be at normal speed. If I have DDR400 RAM, its running at 200Mhz right. So does that mean my processor is actually underclocked because the FSB is set at 200Mhz also?
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  1. P4 chips use the 4 pipeline bus. The FSB of a P4 chip is 4-times the system clock. In your case a P4 533fsb chip has a default system clock of 133 since 133x4 is 532 you get the 533 fsb chip. When overclocking this chip, upping the system clock is the only option. Using ddr400 is good since it can support up to 200 on the system clock if you keep the 1:1 ratio. DDR 400 is 200 clock but DDR is double data rate in which the ram has 2 pipes thus gett 400mhz from the ram. Do not compare the bandwidth of the ram to the CPU for intels since intels use 4 pipes and DDR uses 2 pipes.

    Check in you bios for the CPU clock and RAM clock. These 2 are diffent worlds but are put together by the system clock. Let say if you can run the chip to 200 on teh system clock, that would mean it is running at 800fsb and would be in sync with the ram as a bonus.

    "So does that mean my processor is actually underclocked because the FSB is set at 200Mhz also?"

    No it is not but it is slower on the system clock if you do have the ram set at its max of 200 system clock.

    "If I have DDR400 RAM, its running at 200Mhz right."

    Yes that is correct.

    For OCing the P4 chip, just keep upping the sytem clock till it tanks then drop it down a few mhz. Should be able to get about 166 which will give the CPU a 664 fsb. In ram terms this is about PC2700 or ddr 333. I can talk more but want you to assimilate this infor first then ask more later if needed.

    You can keep the cpu and ram different on intel boards so dont worry if the cpu clock differs from the ram, just dont exceed the ram's max system clock or you will get software corruption of the whazoo. You may also wanna do some research on OCing from other places that have OCed with the same stuff to give you a base plan.

    Mobile Barton 2500+ @ 2420mhz 11x220 1.7v
    Asus A7N8X Dlx 440 FSB
    1gb Geil GD pc3500 Dual Channel (2-3-3-6)
    Segata 80gb SATA 8.5ms seek
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  2. My mobo doesn't seperate the cpu and mem frequencies. I have a gigabyte 845PE 667Ultra. Or wait maybe it is serperate. I don't know you tell me. I set the cpu freguency to 100Mhz so it would run at 400mhz because it set my mem frequency 200Mhz. I only have PC2100 which is 133Mhz right? But when the memory test comes up when I first boot is reads 266Mhz I believe. It could be DDR266, guess I'll have to check.

    Oh by the way thans for all the information and trying to help me.
  3. "I only have PC2100 which is 133Mhz right?"
    Yes

    "I set the cpu freguency to 100Mhz so it would run at 400mhz because it set my mem frequency 200Mhz"
    That sounds right. The base sytem clock was set to 100 thus the CPU took that and multiplied it by 4 getting 400 and the ram took it and multiplied it by 2 getting 200.

    Most Intel board can differ the CPU clock and the RAM clock, called the CPU:RAM Ratio. If you have a 533 FSB CPU with PC 2100 RAM, they your base system clock is currently set to 133mhz.

    Mobile Barton 2500+ @ 2420mhz 11x220 1.7v
    Asus A7N8X Dlx 440 FSB
    1gb Geil GD pc3500 Dual Channel (2-3-3-6)
    Segata 80gb SATA 8.5ms seek
    ATI Radeon 9800 Pro to XT(463/795)
  4. I checked the bios when it does the RAM check and it says 266Mhz even though I set it at 200Mhz. I guess the Bios is setting RAM clock speed automatically? Anyways, I want to upgrade someday when I get money to a P4 with HTT(Hyper Threading Tech). What is good RAM for a 800Mhz bus? Will PC3200 still be okay?

    Wait i just realized. With 800Mhz all you would have to do is set the FSB to 200Mhz and your set right?
    <P ID="edit"><FONT SIZE=-1><EM>Edited by Hellrazor on 08/19/04 08:15 PM.</EM></FONT></P>
  5. Why yes it is. PC3200 has a max system clock rating of 200mhz and the 800fsb P4s operate at a 200mhx system clock. You will be able to get the 1:1 ratio.

    Youre only concern is what memory bank support your new mobo will support. Does is support single-bank, twin-bank, or both? Banks are which side of the ram waffer has chips. The you ram is chips on both sides of the waffer, then it is twin bank and you need to find mobo that supports twinback memory or both. Also you needs to find out how many banks that mobo can take for each bank on the ram is a bank on the mobo consumed. So if you have a pair of twinbank ram then you a mobo that has at least 4 banks and supports twinbank memory. Questions?

    Mobile Barton 2500+ @ 2420mhz 11x220 1.7v
    Asus A7N8X Dlx 440 FSB
    1gb Geil GD pc3500 Dual Channel (2-3-3-6)
    Segata 80gb SATA 8.5ms seek
    ATI Radeon 9800 Pro to XT(463/795)
  6. only other question I have is what mobo do think is a good one. I was told/thinking about Abit IS7. Still debating though, on whether I should just wait till the athlon64 has got its kinks worked out.
  7. Generally Ctrl-F1 in the BIOS will open up extra options on the Gigabyte board, that should give you full control over everything.

    My Desktop: <A HREF="http://Mr5oh.tripod.com/pc.html" target="_new">http://Mr5oh.tripod.com/pc.html</A>
    Overclocking Results: <A HREF="http://Mr5oh.tripod.com/pc2.html" target="_new">http://Mr5oh.tripod.com/pc2.html</A>
  8. I thought while I am asking questions about P4's maybe someone could tell me what the socket LGA 775 is all about and how it compares to the regular socket 478?
  9. Matching speeds 1:1 on a P4 with a single channel board is one of the WORST configurations. Contrary to AMD, the best setting for a P4 single channel is 1:2 CPU:RAM. And in case you missed it, he has a single channel chipset. Also, Twinbank is nForce2, good P4 chipsets have Dual Channel.

    <font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
    <font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
  10. A few things you'll need to know:

    1.) The 533 bus is QDR x133MHz. It uses a 133MHz clock speed, which is usually what BIOS reports
    2.) DDR400 runs at 200MHz clock speed. That's a higher clock speed than your CPU bus, but a lower data rate. The best configuration is to match bandwidth between the two, but I doubt your board support the ultra-expensive DDR533 RAM.
    3.) The BEST ratio for YOU right NOW is CPU:RAM of 2:3, which is 133MHz CPU bus clock and 200MHz RAM clock.
    4.) BIOS on new boards usually refers to the DATA RATE of the memory, but USES the bus speed (which you don't see).
    5.) To get into advanced BIOS features on a Gigabyte board, you have to enter a key combination from WITHIN BIOS. I think it's ALT-F1, but I can't remember for certain. You may need those added settings to set your asynchronous CPU:RAM clock.
    6.) You won't get a significant improvement from running an 800 bus P4 with a DDR400 single channel compared to a 533 bus P4 with DDR400 single channel. The reason is that the memory is the bottleneck. But the faster CPU with HT provides some improvement in performance even though the RAM performance stays the same.

    <font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
    <font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
  11. That is wat I am waiting for. A64 smoke the P4 platforms but just have issues with a few minor bugs, when Windows XP-64bit comes out.

    <i><font color=red>Only a overclocker can make a computer into a convectional oven.</i></font color=red>
  12. Really nothing but a different precott chip with the standard 1mb cache. Really isnt any difference, well at least from the scores I get and reviews I read.

    <i><font color=red>Only a overclocker can make a computer into a convectional oven.</i></font color=red>
  13. Zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz


    Zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

    <i><font color=red>Only a overclocker can make a computer into a convectional oven.</i></font color=red>
  14. Abit IS7 is dual channel, with your current CPU it would have a 1:1 bandwidth AND frequency ration running your 533 processor and a matched pair of PC2100 modules in slots 1 and 3.

    <font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
    <font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
  15. Crashman, I am in a similar situation. What do you suggest?

    I have:

    P4 2533MHz 533FSB w/ Areoflow fan
    Asus P4PE (MB supports 800FSB) -- single channel :(
    512MBx2 DDR400 Corsair Value Select (CAS 2.5)

    I am wonder what is the best settings I could use for an overclock. I want the best performance, so if that means running the RAM at 200Mhz, or overlocking the CPU and running the RAM a little slower that is fine--I just want the best STABLE performance for my rig. I have read up quite a bit on OCing, but want some expert advice before I start messing with my system.

    What ratio do you suggest and what should I be aiming at with this overclock in your opinion?

    Thanks for the help :)
  16. The ideal speed would be 133/200 (533 CPU bus, DDR400). But since you're overclocking, you'd better set the memory speed as "333MHz", which is actually the data rate for 166MHz memory clock rate. Unless your board shows ratios instead of speeds, then the ratio for that setting would be CPU:RAM of 4:5.

    At 166MHz (DDR333), the RAM will reach its rated DDR400 at a CPU bus speed of 160MHz. That would make a 2.53GHz P4 run 3.04GHz, which might be just a hair beyond its capabilities, but you could always find the CPU's limit (perhaps at 150MHz CPU bus) and use that with the memory slightly lower than its rated speed.

    <font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
    <font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
  17. Thanks Crashman! That is what I was thinking :) Thanks for the time, advice, and experience you share--much appreciated!
  18. My board supported 355 (177.5MHz) for the RAM, so I set it to that, and then overclocked the system so the RAM was at 200MHz.

    CPU: 2850MHz
    RAM: 200MHz (i.e. DDR400)
    FSB: 150MHz (i.e. 600FSB)

    I am running Prime95 and testing everything out... looking good.

    Got to 56 degrees on a full load with stock fan, so I just put in the Ventari Aeroflow (which is LOUD)...

    Ok, been running about 15 minutes... is going between 49-53 with Prime95 running. I am using the Asusprobe program to check the temps.

    The system seems to be a bit quicker (I think that has to do with the RAM)... I may try some other overclock combos after running Prime95 for a bit, but I think the current setup is working nicely :)

    Thanks for feedback and assistance guys :)
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