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whodunnit: motherboard dead

Discussion in 'Electronic Basics' started by [email protected], Jan 6, 2005.

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  1. Guest

    Hey folks,

    My new motherboard died after only a couple of
    weeks on duty. The vendor says he owes me nothing,
    the motherborad was ok, it died of a power surge.

    Let's see:

    - the wall outlet for my PC is properly grounded
    - the monitor on the same outlet was not affected
    - a serial modem on the same outlet was not affected
    - the power supply unit in the PC was not affected
    - a SW receiver on the same outlet was not affected

    Is it still possible that some power disturbance killed
    the motherboard (and the motherboard only) and how?


  2. Extremely unlikely. Most power surges damage the power supply, not
    the mother board, unless they come in through some peripheral device.
  3. Bill Stock

    Bill Stock Guest

    I gather this is a FrankenPuter (Homebuilt)? How do you know it's the MB and
    not the RAM or CPU? If you installed the CPU yourself, it's quite likely a
    heat problem. If the unit was prebuilt, your vendor needs to get stuffed.
  4. w_tom

    w_tom Guest

    The power disturbances include static electricity when you
    assembled it weeks ago, transients that enter into mother
    board from safety ground, and a power supply this is missing
    essential safety functions (very common with power supplies
    sold on price and without numerical specifications).

    Without specific facts, such as which component on
    motherboard that is damaged, then no one can answer your

    Power surges are rare events that occur typically once every
    eight years. Four adjacent devices can all be confronted by
    same transient. But if only one device provides both an
    incoming and outgoing path for that transient, then only that
    device destructively conducts the transient.

    Furthermore since so many don't even know if a power surge
    existed, what is it, and how it damages electronics, then the
    power surge is that classic salesman excuse. Did a power
    surge ever occur? How would you know? How would the salesman
    know? Power surges (like heat) are the poor excuse on which
    blame is cast. After all, who is going to prove that
    accusation wrong in a world where most don't have electrical

    Far more likely, especially this time of year, is damage
    from static electricity.

    And then so many other usual suspects exist including other
    defective components, motherboard conductive standoff breaking
    through solder mask and now touching a printed circuit trace,
    and infant mortality.

    Without facts, no one can answer your question. You have
    not even taken voltage readings from the power supply - the
    first fact one obtains.
  5. Jim Douglas

    Jim Douglas Guest

    Typically most decent places will replace a board this new, and typically
    boards that are bad do so within the first 3 months of usage.
  6. Rodney Kelp

    Rodney Kelp Guest

    You should get a good UPS with filtering and spike protection. Much safer
    than a wall outlet. Static (6000v) could fry something especially now with
    so many USB external components. It could have just failed on it's own also.
  7. Guest

    I'll follow up on your hint that the power supply
    unit may be a cheap one lacking essential features.
    [Any models recommended?]

    Otherwise, I think I was careful with static
    electricity and in any event its effect would not
    have taken a 4 week delay. Also the processor

    The problem was at first a wobbly boot: the
    machine would start and stop within a few seconds,
    fans still turning. To complete the boot, I pushed
    reset. Then one day nothing, just the peace of



  8. I would be asking the dealer how he could determine the 'surge' ocurred and
    perhaps show you the damaged components.
  9. w_tom

    w_tom Guest

    You are correct that static electricity probably is not
    reason for failure. But static electricity creates
    overstress. Overstress results in parts slowly getting worse
    days or months later. Yes, static electricity does remain a
    possibility. Just not a more likely reason for failure.

    More likely is infant mortality. IEEE Spectrum in a recent
    issue featured a cover story on why the human body fails.
    Charts there demonstrate how infant mortality causes so many
    failures in so short a period - and a general trend on when
    failures happen.

    Now for another lesser reason for failure. Does the power
    supply manufacturer provide a long list of numerical specs.
    How to suspect the worst (in any technical product). The
    manufacturer so fears you might learn facts as to deny you
    those facts. In reality, maybe one percent of consumers
    understands specs. But without numerical specs in the hands
    of all, then the one percent is disempowered. IOW no long
    list of numerical specs - then suspect a scam. The one
    percent cannot sound the alarm.

    An abridged list of specs that any responsible power supply
    manufacturer provides. If no numbers, then assume they are
    hiding something - missing essential functions:
    Specification compliance: ATX 2.03 & ATX12V v1.1
    Acoustics noise 25.8dBA typical at 70w, 30cm
    Short circuit protection on all outputs
    Over voltage protection
    Over power protection
    100% hi-pot test
    100% burn in, high temperature cycled on/off
    PFC harmonics compliance: EN61000-3-2 + A1 + A2
    EMI/RFI compliance: CE, CISPR22 & FCC part 15 class B
    Safety compliance: VDE, TUV, D, N, S, Fi, UL, C-UL & CB
    Hold up time, full load: 16ms. typical
    Efficiency; 100-120VAC and full range: >65%
    Dielectric withstand, input to frame/ground: 1800VAC, 1sec.
    Dielectric withstand, input to output: 1800VAC, 1sec.
    Ripple/noise: 1%
    MTBF, full load @ 25°C amb.: >100k hrs

    How top dump power supplies into N America at higher
    profit? Forget to include essential functions. Then sell the
    power supply at $25 or $40 retail. A minimally acceptable
    power supply has a full retail price of $65. Just another
    number that should create suspicion.

    Concept does not stop with power supplies. Concept even
    works for cars. Pontiac is hyping performance. So why do
    they not provide both horsepower and liters on the sticker
    sheet? Because Pontiac engines remain some of the lowest
    performance in the industry. Even the greater noise suggests
    their low performance. Just another example why the
    manufacturer would hide the numbers. Do the horsepower per
    liter arithmetic yourself. Numerical facts that the
    manufacturer hopes you will not learn.

    Your computer symptoms only say, "Time to collect facts".
    In your case, I would start with a 'usual' suspect - the power
    supply 'system'. Not just the power supply. System includes
    controller on motherboard. To understand the 'system', you
    need a tool as essential as a screwdriver - a 3.5 digit
    multimeter. Concepts to better understand why boot fails are
    delineated in: "Computer doesnt start at all" in
    alt.comp.hardware on 10 Jan 2004 at
    "I think my power supply is dead" in alt.comp.hardware on 5
    Feb 2004 at .

    Another poster here demonstrates how myths are promoted. He
    recommends a UPS to stop spikes and surges. Even the
    manufacturer does not make that claim. Will the relay inside
    a UPS that takes tens or milliseconds to respond stop a
    destructive spike that is completed in microseconds? Again,
    how numbers expose a myth - such as a plug-in UPS for hardware

    Everything needs a number, or at least a numerical
    relationship. Without numbers, then only speculation
    remains. Your motherboard supplier demonstrated classic
    speculation. Typically destructive power surge occurs about
    once every eight years - another number that varies regionally
    and locally. Many who don't know anything about electricity
    hype myths such as daily surges. They just 'feel' these surges
    must exist. If daily surges exist, then we were trooping to
    the hardware store everyday to replace destroyed electronics -
    even 30 years ago.

    Notice the need for numerical information. Compare that to
    what you provided AND what your supplier concluded. A more
    likely reason for your failure is infant mortality or a
    failing power supply. But without numbers, we can only
    speculate. Provided are how to get numbers. Even if you
    don't understand those numbers, still, those numbers make it
    possible for others to provide useful responses. No numbers
    means wild speculation - or maybe a scam. No numbers is why
    another poster recommended the plug-in UPS.

  10. Bill Stock

    Bill Stock Guest

    Sounds like it might be a bad PS. I had one flake out slowly, where the
    system kept freezing up.

    If it's an AMD CPU, you can check their website for recommended power
    supplies. Intel may have similar info.

    See if your dealer will let you 'borrow' a power supply to test your theory
    or better still get him to do it for you. I've had several bad boards when
    putting together systems, several from one vendor. (Stopped dealing with
    them). Others vendors make you jump through the return hoops and will
    eventually send you a refurb months later. The latest vendor tests the dead
    board on the spot and hands you a new one. But I've only ever had ONE dead
    board from them. Some vendors resell dead boards hoping to get rid of their
  11. w_tom

    w_tom Guest

    Borrowing or swapping power supplies takes longer, puts the
    system at greater risk, and my only mask the original
    problem. The faster and cheaper procedure to first identify
    the problem - and one always wants to identify the problem
    before changing any parts - was posted previously in at: and

    Problem sounds like a bad power supply. It also sounds like
    a bad power supply controller. It also sounds like a bad
    power switch. It also sounds like bad motherboard

    First get facts before speculatively replacing anything.
    Saves money. Saves time. Solves problem the first time. And
    teaches a human the 'whys' about computer failure.
  12. Guest

    Thanks a lot, Tom, but you are ways above me.

    Even if (big if) I manage to do all those
    measurements you insist on, what would be the
    practical consequence? Discard motherboard and PSU
    until you get products with good test values.
    Sorry, I'm not even trying. I bet you don't do it

    My PSU was indeed cheap chinese junk. So dirty
    power and junky PSU may give an explanation of
    what happened, some building up of damages over

    I'll get a good PSU for my new motherboard and
    I'll get an UPS, although you seem sceptical in
    this respect. Surely better than nothing?


  13. w_tom

    w_tom Guest

    Those voltage measurements may be performed by junior high
    school science students. There is nothing complex, difficult,
    or expensive in what was posted. In fact, measurements can be
    accomplished in just minutes. Far longer to read and learn
    what must be done. IOW the knowledge is that powerful and
    useful. As another once said, "the only thing you have to
    fear is fear itself". Get the meter. A tool as essential to
    computer work as a screw driver. So ubiquitous as to be sold
    even in Home Depot, Lowes, Sears, and Radio Shack.

    In the meantime, a UPS is for data protection. Hardware
    protection that works at the appliance is already inside the
    appliance - as required by industry standards. Protection
    that may be overwhelmed IF destructive transients are not
    earthed before entering the building. The UPS costs what -
    maybe $100 - and to only protect one appliance? Ineffective
    hardware protection as made obvious even in manufacturer's own
    numerical specs. The UPS is only for data protection and not
    for hardware protection.

    Effective hardware protection costs about $1 per protected
    appliance. Installed to protect everything. Superior
    protection especially for the computer. With a 'whole house'
    protector, then a surge will be earthed before it can
    overwhelm internal computer protection. One effective
    protector sold in Home Depot is Intermatic IG1240RC. For
    hardware protection, spend less money for a protector that
    really works - because it makes a short and so essential
    connection to earth ground. A UPS for hardware protection is
    too often recommended by those who don't even know how
    electricity works. Where is the earth ground to that UPS?
    Just a concept the UPS manufacturer instead avoids. A
    protector is only as effective as its earth ground.
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