Whats the Performance Limiter?

RWBRWB Icrontian
edited September 2003 in Hardware
The system bus can only handle so much, so once you reach certain levels on the CPU FSB to the Memory Bus, isn't there a point in which overclocking the RAM more doesn't help much?

Such as, I have a P4 2.4B it is running 157MHz(x18) right now, my CURRENT memory runs 418 or something. With the x4 multi onthe CPU Bus I have 628MHz FSB.

Does my memory need to his that same level to reach my CPU's limit? Cuase only so much information can pass at one time and stuff right?

My new MB supports Dual Channel, now if I were to buy x2 new sticks of RAM the BUs is doubled right? Say x2 sticks of DDR433 in dual channel is running at double the speed of 866MHz right? Therefore going above and beyond my CPU Bus and not actually doing that much more for my performance since my CPU bus is only at 628?

I think I just went crosseyed

Comments

  • ThraxThrax 🐌 Austin, TX Icrontian
    edited September 2003
    1) If you're running synchronous bus (And you aren't), FSB always helps.

    2) The larger the difference between your FSB and your RAM speed, the smaller the performance gain (Throws the cycles out of synch.)

    3) With p4s, an <i>a</i>synchronous bus still is beneficial, highly so. The faster you run your memory, the better performance you will get. But see #2.

    4) The bus WIDTH is doubled, not the memory speed. If you bought DDR433, you'd still have 216MHz memory, you would just have double the bandwidth now. Instead of 3,456MB/s of bandwidth, you'd have 6,912MB/s of bandwidth.


    I hope I answered most of your questions. Your post was hard to figure out. :confused:
  • RWBRWB Icrontian
    edited September 2003
    Synchronus being that my CPU FSB is at 157 and my RAM Speed is also at 157?
  • ThraxThrax 🐌 Austin, TX Icrontian
    edited September 2003
    Right. :)

    If you have a synchronous bus, every bit of data in the memory or CPU can be exchanged every single oscillation of the clock. If you have an <i>a</i>synchronous bus, sometimes bits of data have to wait for the clock to oscillate again meaning that all the data isn't going through precisely when it needs to. This can slow things down, but the effect is slightly less noticeable (And actually tends to speed things up) in the higher ranges of FSBs.
  • RWBRWB Icrontian
    edited September 2003
    Hrm... ok.

    So what is the best method for my system?

    Right now I believe the highest my CPU will go is 157MHz x 18, so when I get my new RAM in which is going to be Geil Golden Dragon 5ns PC3500(2x 512MB sticks), what RAM speed is best for my system?

    My systems has multiple dividers, like 15 or so.
  • RWBRWB Icrontian
    edited September 2003
    Pentium 4 2.4B/ Swiftech MCX4000-B w/ Y S Tech TMD Magnetic Drive Fan @ 10K RPM's / Gigabyte SINXP1394 P4 Titan Motherboard / x1 Corsair XMS PC3500 @ 418MHz 2-3-3-6-T1 / x1 Maxtor 40GB Liquid Bearing ATA133 8ms HDD's / Abit Siluro Ti4600 @ 320/675 / TTGI 520W PSU Model TT-520SS Triple Smart Fans / Lite-On DVD 16x48 & Lite-On CDRW 40x12x48 / TEAC FDD / Windows 2000 Pro SP4

    Those should be my updated system specs
  • ThraxThrax 🐌 Austin, TX Icrontian
    edited September 2003
    Are you sure you want to get a Gigabyte board on a P4? There's considerably better out there, for ANY platform. Or, if you already have it, Shorty and I send our condolences.

    When you get your new memory, back down the multiplier and place the FSB up, toy with dividers. I can't really tell you what'd be best for your system.
  • RWBRWB Icrontian
    edited September 2003
    I'm happy with my Gigabyte board, I was happy with my last one so I got this one, and I had originally upgraded FROM Abit.

    It's fast, haven't had but one problem with them.

    Besides, next year I am getting a dual opteron system anyways :P
  • edited September 2003
    Thrax said
    When you get your new memory, back down the multiplier and place the FSB up, toy with dividers. I can't really tell you what'd be best for your system.

    Uhh Thrax, this is a Pee4 we are talking about here, with a locked multiplier. ;)

    RWB, I looked it up on Gigabyte's website and I see your board uses the SIS 655 chipset, which is a dual channel DDR board. Running DCDDR, your theoretical mem bandwidth in DC mode is equal to the theoretical requirements of your P4, so trying to run the mem speed faster than 1:1 won't help you and it might actually give you a performance decrease, due to running your mem asych to your proc, as Thrax has already posted about. If the max fsb speed you can run your proc at is 157, then PC2700 would actually do you just fine. What you can do though is run the proc/mem at 1:1 and tighten the mem timings and you should see some more performance increase. You should definitely see some performance gains going from single channel to dual channel though.

    Don't let them mess with you too bad about your Gigabyte board RWB, they have made some good boards too. I have a GA-6OXET board, which is one of the 2 best mobo's ever made for Tualatin procs (the ST6 is the other 1). In December it will be 2 years old and it still kicks mucho ass for a P3.:thumbsup:
  • ThraxThrax 🐌 Austin, TX Icrontian
    edited September 2003
    Right. Pentium 4, forgot they screwed their consumers in that manner. ;D
  • RWBRWB Icrontian
    edited September 2003
    Arn't AMD doing similar methods to prvent you to unlock your Multi? Intel was merely more sucessfull at doing this.

    But either way, I want a Opteron NOW!

    I'll run some tests to see what results I get.
  • ThraxThrax 🐌 Austin, TX Icrontian
    edited September 2003
    They covered the bridges, you can still:

    -Paint pins underneath the processor
    -Wire the processor pins together to unlock
    -Scrape the coating off and unlock
    -Use an nForce2 board
  • a2jfreaka2jfreak Houston, TX Member
    edited September 2003
    Even if Thrax was wrong in saying "back down the multiplier and place the FSB up" RWB should be able to back the FSB/RAM ratio down to run the RAM slower than the FSB.
  • RWBRWB Icrontian
    edited September 2003
    Just ran my RAM at 314MHz and lost a hundred points or so in 3D mark 2k1, mind you that is with all quality levels at normal gaming level, so I went from a 5334 point score to 52xx score when I rebooted. Not much for a 1hundred MHz decrease in Memory speed. So I figure it does matter, I have more testing and work to do to further figure this out.
  • RWBRWB Icrontian
    edited September 2003
    OK I have tried various approaches and have found that no matter what I do, my CPU just sucks(yeah I know it is a Pee4 issue).

    I guess I have 10 choices...
    01) When I buy my new memory tomorrow I could go with DDR333 since the performance gain is fairly neglegiable with my CPU stuck at 157MHz

    10) If I find a good price/performance and as long as it is better than what I have, I go back to a Athlon system which means, New Board, New CPU, and new Heatsink, along with the new memory I wanted, which would probably betoo expencive for me to handle at the moment.

    Looks like I am going to be looking at newegg.com for a while :P
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