P5AD2 Power Supplies

Discussion in 'Asus' started by Drew Zerdecki, Dec 16, 2004.

  1. I am shopping around for ATX cases for this motherboard. I am looking
    for a hometheater case and am looking at a Cooler Master desktop
    case(Cavalier 2). However the case comes with a 300W PSU (Macron
    MPT-301, ATX 12V.) Would this PSU be OK? Would I just need a 20 to 24
    pin cable? Or do I need to buy another PSU and find a case that doesn't
    include a PSU?

    Thanks for your help! Feel free to recommend other cases, or mobo for
    that matter!

    Drew Zerdecki, Dec 16, 2004
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  2. Drew Zerdecki

    Paul Guest

    If you have a very minimal config, it might work. Like an ATI 9000
    or a Nvidia FX5200 video card, and a 2.8Ghz processor, might be
    quite happy with the 300W supply.

    But, if you think to the future, you'll be replacing that supply
    before the dust has had time to settle on it.

    If you want a PSU estimator, try this site:


    This estimator will overestimate the amount of power
    required, but that means, at least, the power supply you buy
    will have some margin against uncertainty and age.

    I feel sad for all the computer cases that come bundled with
    cheap/weak power supplies, because it means we're filling the
    landfill with product that never gets used. It would be so much
    better if cases came unbundled, but that is not the trend.

    Paul, Dec 16, 2004
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  3. What about a 3Ghz processor and a fx5200, pvr250, pvr350, and 1-2
    hardrives? 300? 350? 400W?

    Yeah it does suck that they give you a bad power supply. So now I have
    to by a cool case for $115 then $50-60 PSU?
    Drew Zerdecki, Dec 16, 2004
  4. Drew Zerdecki

    Paul Guest

    I have a FX5200 and it is a cool running video card, even when
    you are gaming on it. At least the 64bit memory interface version
    is cool, the 128bit memory interface cards might run a bit warmer.

    Power supplies have two kinds of ratings. The total power is
    a useless metric, as a computer never comes close to exceeding
    the total power. For example, a computer might draw 150W from
    a 350W supply, when gaming. But, the part that does count, is
    the individual power outputs. Each of +3.3, +5, and +12V have
    separate ampere rating, and that is the thing that is critical.
    On a P4 or an Athlon64, the most current comes from the +12V
    rail, while an AthlonXP draws power from +5V as a rule.

    For a basic system, I'd want [email protected] for a P4. The Intel 530
    (P4 3GHz LGA775 socket) has a TDP of 84 watts, and when that power
    is pulled from 12V, that is 7 amps. The Vcore power converter
    that turns the +12V into processor juice, is about 90% efficient,
    so the power coming from the supply becomes 7.77 amps. Allow
    0.5A per hard drive (idling), that is 1 more amp. The case and
    CPU fans could draw an amp. Now we're close to 10 amps. Many
    PCI cards draw on the order of 1W from +5V, and unless you have
    a really special function on the card (like the old co-processor
    cards, which had a Pentium and memory on them), I really don't
    count the power of plugin PCI cards. A supply with 15A output
    should handle that load with ease (at least until you buy a
    top end video card). A supply with only 10A output on +12V,
    will be under a strain. The other two rails (+5V and +3.3V) on
    all the supplies I've looked at, are strong enough to meet the
    maybe 10 to 15 amps drawn from those rails at the best of times,
    so I wouldn't expect a problem there. The only time the +5V
    might be getting close, is for people building AthlonXP
    systems (in that case [email protected] is handy to have, especially if
    using a hot video card).

    If you want to look up the processor power for yourself,
    there is processorfinder.intel.com or you can get a
    processor datasheet from developer.intel.com, like this

    (TDP is listed on page 74.)

    As far as computer cases go, I don't know what country you
    are in, but you could start by visiting the Newegg.com site,
    as they have a large selection. (I cannot shop there, because
    they won't do business with Canadians.)

    This is the "shop by catagory" for computer cases:

    If you select "no PSU" and do a search, there are 221 cases
    listed. Make a note of the brand names and model numbers,
    if any, and use those as search terms for businesses within
    your local area. At the top of the page, the "by manufacturer"
    lists CHENMING (38), LIAN-LI (26), SILVERSTONE (21) and
    that implies that those cases are widely available without
    a PSU. The prices start at $17 and go up to $300 for a computer
    case shaped like the Eiffel tower.


    The last case I bought was an Antec Sonata. That comes with a
    380W Truepower supply. But I really cannot say I'm that fond of
    the case - the drive bay that mounts sideways isn't actually
    that good an idea, the air flow sucks (I've removed the front
    bezel to let it breathe better), and the 120mm fan they put
    on it was a waste. If anything, the 120mm fan should be pushing
    air into the case (i.e. be front mounted), instead of pulling
    air out the back of the case. The case has a nice finish, but
    that is perhaps the most positive thing I can say about it.

    Recommending cases and power supplies is a losing proposition,
    as they all have their shortcomings. The best way to shop for
    them, is visit your local computer stores and "kick the tires".
    You won't know what you like until you look inside the cases.
    For example, once I saw how flimsy Lian-Li was, I no longer
    get excited when I see one pictured on a web page. I'm a
    "beige steel case" kind of guy :)

    The Newegg site has extensive pictures for each product, so
    if you click the picture of the product, you should eventually
    get to a web page where there are perhaps six views of the
    product. You can see a fair amount of detail in those pictures,
    and that may help you make a decision.

    With regard to power supplies, I probably would have recommended
    a Truepower to you, but again, the longer I own mine, the more
    I'm convinced it is nothing special. Based on people's experiences
    with Enermax, I'd judge them to be in the same camp. This doesn't
    leave a lot of good alternatives. (What I expect from a supply is:
    no obnoxious smell, no acoustic effects when the CPU is loaded
    down, a fan speed that keeps the PSU cool, and maybe even an
    honest power rating on the label. - I'm very hard to please.)
    Fortron/Sparkle is a possibility - some models look good, and
    the Heroichi I had was OK as well. PCpowerandcooling is the
    Cadillac of the industry, but very few people can afford to
    buy one of those, so you won't find much feedback on their

    Some day I'm going to build my own power supply. It'll only
    cost $600, but it will be worth it :)

    Paul, Dec 17, 2004
  5. WOW. Thanks very much for the info!
    Drew Zerdecki, Dec 17, 2004
  6. another follow up:

    If only get the 300W, is there a way to check what the power ratings are
    after I get the system up and running? For instance, to make sure I am
    not cutting it too close?
    Drew Zerdecki, Dec 17, 2004
  7. Drew Zerdecki

    Paul Guest

    The rating of the power supply is printed on the label on
    the side of the power supply casing.

    I measure the power consumption of my computers with a
    clamp-on DC ammeter, as it is a non-contact device that
    measures current by means of the detected magnetic field
    around each wire. It means I don't have to disturb any
    wiring to use it. That is one way to measure the current.

    This is a very similar model to the one I use:

    Current can also be measured by placing a sense resistor in
    series with each wire. Then measure the small voltage
    across the resistor and determine the power that way.
    You would have to make a cable assembly with the resistors
    inserted in the current flow path. The toughest part of
    that measurement, would be the tiny voltages (maybe 50mV
    or so). The resistors for the current measurement wouldn't
    be cheap either - if you make a resistor out of copper
    wire, the copper has a significant temperature component
    in its resistance, so you would need to measure the
    temperature of each resistor, to calculate a compensation
    factor for the resistor. There are some alloys that have
    a low temperature coefficient, but they are expensive, and
    would make the project cost about $100 for the cable assembly.
    So, compared to the clamp-on DC ammeter (uses a Hall probe
    inside), the resistor method is messy.

    There is no built-in capability in any computer I've seen,
    to measure power consumption.

    Paul, Dec 17, 2004
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