How can I compare single and dual channel Ram performance

Discussion in 'Asus' started by timO', Sep 30, 2006.

  1. timO'

    timO' Guest

    I am building a PC and so far obtained P5WD2-E PREMIUM mobo; my D-805
    cpu; a WD2500KS hdd; and am now shopping for a case, cpu cooler,
    DVD-CD/RW, and RAM
    I'm blowing the budget, and I have to throttle down my spending spree.

    I was initially thinking of 1 GIG of DDR2-800.
    Now I'm wondering how dual channel affects performance, since the
    slower chip are cheaper and might provide comparable performance when
    used in a dual channel configuration.

    I'm also confused about the wisest choice in case and PSU. I know I
    want at least 500W, but some cases come with a PSU included, and are
    cheaper than standalone PSU's.
    Also I see memory and cases etc. on eBay, especially used RAM, and
    wonder if it's a chance I want to take.
    cpu coolers. I don't want to install plumbing, but wouldn't mind
    enhancing the stock setup. But it has to fit into the case.
    I plan to install windows XP pro corporate 2002.
    Any positive feedback or suggestions would be much appreciated
     
    timO', Sep 30, 2006
    #1
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  2. timO'

    Major Ninth Guest

    you should have gone with a E6300 cpu. Take a look at the sonata II case
    w/450w supply. With the conroe or allendale cpu (E6300), you would not need
    a 500W supply, unless your were planning on running crossfire or SLI video
    and lots of drives. For low cost high performance video check out the 7600GT
    video cards.

    -john
     
    Major Ninth, Sep 30, 2006
    #2
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  3. The best CPU cooler is the Zalman CNPS9500.

    Did you already have the motherboard, or did you buy it recently? If
    you bought it recently, you'd have been better off with a system based
    on (or that would at least support) Core 2 Duo.

    Don't buy used memory UNLESS it has a "no DOA" guarantee and it comes
    from a reputable seller.
     
    Barry Watzman, Sep 30, 2006
    #3
  4. timO'

    Paul Guest

    Maybe you've been using this article as a guide ?

    http://www.tomshardware.com/2006/05/10/dual_41_ghz_cores/index.html

    I think a lot of people see 3.5-3.6GHz, due to thermal/power
    issues.

    The difference RAM makes, can be seen here. Running a high
    RAM clock doesn't look like that much of an advantage.

    http://www.anandtech.com/memory/showdoc.aspx?i=2732&p=4

    I notice in the Tomshardware article, that the motherboard
    is using variable strapping to provide RAM dividers. As
    the FSB clock goes up, the motherboard seems to offer
    different dividers, and I think that allows any RAM you
    could want, to run.

    I think the power situation on overclocked D-805 systems
    is a lesson in astronomy. Consider the data in the Toms
    article:

    First, start with the Intel data:

    95Watts at Vcore of 1.25-1.4 volts
    http://processorfinder.intel.com/details.aspx?sSpec=SL8ZH

    As best as I can determine, by reading the Toms article:
    (I'm not 100% positive on all these. Their writing style sucks.)

    Freq VID_Voltage_used My Estimate

    2.66Ghz 1.337V Nom = 95W
    3.33GHz 1.337V
    3.6 GHz 1.337V ? (Toms thinks power doubled?) 128.6W
    3.8 GHz 1.500V 170.8W
    4.0 GHz 1.5625V ? 194.7W
    4.1 GHz 1.675V 229.8W

    My calculated value is based on Power = F*C*V**2. If Intel
    thinks the processor uses 95W at Toms nominal VID of 1.337V,
    then other powers can be worked out by multiplying the
    nominal power by F2/F1 * (V2**2 / V1**2). For example,
    at 4GHz, assuming the VID setting in the BIOS really
    was 1.5625, this would be

    95W * 4GHz/2.66GHz * (1.5625*1.5625)/(1.337*1.337) =
    95W * 1.5 * 1.366 = 194.7 watts

    Thus it is important, when buying equipment for the
    project, to select equipment intended for a particular
    target value. You'd need a bigger power supply, more
    extreme cooling etc., if you aim for 4GHz or higher.

    On a dual 12V rail supply, 12V2 powers the processor.
    Say we aimed for 3.6GHz on air. Then we'd need
    128.6W/12V = 10.7A and this increases to 10.7/0.90
    (assuming Vcore is 90% efficient) or 11.9 amps of
    real current.

    A good fit for that level would be a product like
    this. I selected this because it has an efficiency
    of >80%, meaning the supply generates less heat
    than other supplies, when running all that junk in
    your computer case. While this Seasonic may not be
    exactly right for the project, it gives some numbers
    to work with.

    [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
    http://www.newegg.com/Product/Product.asp?Item=N82E16817151024

    The 12V2 at 16A has a little margin when compared
    to the 11.9 amp calculated figure. But if you do the
    arithmetic, you won't have to go too much farther up the
    frequency scale, before the supply runs out of poop (around
    the 3.8GHz mark). Thus, if you aim for 3.8 or greater,
    then a 600W or higher might be in order. And clearly the
    price of such supplies, is making the savings on the
    D-805, invisible.

    12V1 powers hard drives, CDROM, case fans, and video card.
    If you had the most power hungry ATI video card, that
    draws 10 amps. Allow 3.5 amps for a couple hard drives,
    a CDROM and the case fans. Thus you'd need 13.5A min for
    a high end video, on the 12V1. The above supply seems to
    be prepared for this, at 17A, so maybe the 12V1 won't be
    a limitation to the same extent. Xbitlabs has power
    measurements for video cards, so you can look up how much
    your (unspecified) video card needs.

    If this was my project, I'd have to mull over the
    air cooling solution carefully. The article suggests
    the Zalman 9500, and the first question is, does the
    Zalman 9500 blow any air over the MOSFETs ? Regardless
    of whatever CPU cooler you use, check the MOSFETs and
    coils of the Vcore circuit for overheating while Prime95
    is running, and add fan(s) in the Vcore area if you
    find the components are too hot. This would be
    absolutely essential if you use water cooling, as with
    water, there is no cooling at all for Vcore.

    A Conroe/Allendale might have made this a "tamer"
    experiment to try :)

    Finding a case without a power supply, on Newegg, should
    be pretty easy. On the computer cases page, you can select
    "No" power supply in the search panel. This is a Kingwin
    with a 120mm fan in the back, and you'll need that kind
    of cooling for your experiment. $54. Since there are
    probably 1000 cases on here, you can likely find something
    you can live with.

    http://www.newegg.com/Product/Product.asp?Item=N82E16811170029

    This is a 120mm fan I have in a system. I keep it turned down,
    since I don't need the full 110CFM for cooling. If you find
    your case is too hot, and you have room for a 120x120x37.5mm,
    this thing will fix it. You need enough vent space for inlet
    air on the front of the computer, for this thing to pay off.
    I keep mine at 70% voltage, to keep the noise down :)
    Note that this thing draws 1 amp at full speed, and should
    not be run from a fan header. Being 37.5mm deep, it is a
    bit thicker than your average 120mm fan. Did I say it was
    noisy :) But that is the kind of cooling you need for
    a hot processor and video card. An Arcticcooling aftermarket
    cooler for the video card, one that blows exhaust out of the
    case, might help prevent the inside of the computer case
    from becoming an inferno.

    http://www.circuittest.com/English/Content/Items/CFA1212038MS.asp

    Paul
     
    Paul, Oct 1, 2006
    #4
  5. timO'

    nobody Guest

    I saw a 1000 watt supply the other day advertising itself as Quad
    SLI, Quad core ready. Since 500 watts isn't enough for the more
    extreme SLI/dual core overclocks, one would think that 1K watts
    wouldn't really be enough for quad everything if you turned the
    volume up on everything ;)

    We're going to need some more core shrinks.
     
    nobody, Oct 1, 2006
    #5
  6. timO'

    Paul Guest

    One reason I go into detail in my posts, is to show that
    guessing in terms of the total watt spec on the side of
    the supply, does not tell the whole story. Total watts
    is for all three rails, +3.3V, +5V, +12V, as they are the
    major current carrying rails. The demands on 3.3V and 5V
    have been stable or decreasing with time. The demand on
    12V has been increasing, and in the case of SLI, the
    video cards are making more of a dent in system consumption
    than the processor. There is no reason to assume that
    quad cores will cause the power supply to double in size.

    Paul
     
    Paul, Oct 1, 2006
    #6
  7. Not really, the 1K PSU is measured at real output, not "best conditions"
    output like other PSU's. I have the same brand with a 510 rating, and it
    runs 7 hd's, a dual core CPU, 2 SATA optical drives, a single dual core vid
    card, and accessories and doesnt even breathe heavy. The reason is its
    minimum rating at maximum operating temp is 510w of output. Almost every
    other PSU out there advertises the PSU's maximum output, under ideal
    conditions and non real world operating temps.

    This is why people that purchase these bargain basement 500w PSU's usually
    have so many problems, because in the real world they are lucky to get a
    clean 300w of output, not to mention rails that jump all over the place.
    Purchasing a good PSU is never a bad investment, its the difference between
    building on sand, or building on a rock.

    So when you shop for a PSU, look at the specs, and the temps those specs
    were measured at. Those will give you a real idea of what the PSU's abilites
    are. PC Power & Cooling is the only PSU that I will put in my personal
    machines, and goes into all of my high end builds.

    Dan
     
    Angry American, Oct 2, 2006
    #7
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