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  1. #1
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    Sudden Machine Failure – PSU?

    OK ...

    So a while back my PC just failed on me ... in the middle of using it, it simply switched off, no graceful power down, no sound, no warning at all ... it just switched off. So I thought maybe the system had too much on it (PCI-E video card, 3Gb memory, 4 hard drive array + 1 more drive, 2 DVD drives) .. so, as I was planning to do it anyway, I downgraded to a 2 drive array. Everything worked fine until today ... it did it again,.

    Now as I see it, the fact that the system powers up and switches off BEFORE reaching OS (still in POST) immediately after this until, after a while, it runs again implies a hardware fault ... most likely either the motherboard or power supply. My suspicions is it is the PSU quite simply because the power drop is so sudden, the machine just dies all power off, and I don’t think it’s the power lead since I switched that with no effect.

    The motherboard is an ASUS P5ND2 SLi with P4/S7775/3.4GHz/2M cache, the power supply is an Akasa (good make so I understand, ought to be considering it cost £90) putting out 650W (with true SATA connectors for all my drives i.e. no converters required).

    My problem is, if it is at hardware level, my motherboard has no error logging facility and given that the problem occurs rarely ... how do I test for or otherwise gain information about what the problem is?

    Thanks

    Kyu

  2. #2
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    Re: Sudden Machine Failure – PSU?

    One possibility might be to see how many watts the system unit is drawing by sticking a "power meter plug/socket" device in between the system unit's 13A plug and the 13A socket. Then perhaps you might be able to infer how loaded the PSU is...
    <font face="Script MT Bold"><font color=blue><big><big>John</big></big></font color=blue></font face=script>

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  3. #3
    Uranium Lounger viking33's Avatar
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    Re: Sudden Machine Failure – PSU?

    Kyu,
    I also THINK it sounds like a PSU defect but it's a tough one to prove it.
    John's suggestion is a good one if a Watt meter is available. It should at least show if you are approaching the threshold of excessive power consumption but if the problem is an instantaneous surge that shuts you down, the meter would not be fast enough to show that.
    As always, substitution is the best way to find the cause, IF you have a sub to test it temporarily.

    Another possibility is temperature buildup. Open up the box and see if all fans are working and not being blocked. Clean the fans and exhaust ducts in and a out of the case.

    You might also LEAVE the sides of the case open to see if the increased fresh air flow keeps things cooler.
    Start there?
    BOB
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  4. #4
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    Re: Sudden Machine Failure – PSU?

    > You might also LEAVE the sides of the case open to see if the increased fresh air flow keeps things cooler.

    Most cases I have used lately, leaving the sides off would cause things to run warmer - as it would waste the carefully designed airflow generated by the fans.

    StuartR

  5. #5
    Uranium Lounger viking33's Avatar
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    Re: Sudden Machine Failure – PSU?

    Stuart,

    Possibly, but if you have the AC on in the room, it's worth a try.
    Some boxes don't HAVE carefully designed air flow.
    BOB
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  6. #6
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    Re: Sudden Machine Failure – PSU?

    "My suspicions is it is the PSU quite simply because the power drop is so sudden"
    It may be the PSU, but a sudden power drop really tells you very little. I could be almost anything including cpu themal problems which , when they reach a threshold, can shut a system down suddenly. The reason it might be any number of things is that many power supplies need logic signal(s) from the MB to work.

    On a practical level, the first thing I would do is open up the box and unseat and reseat all cable connections and all cards. If that fails to help, the next thing to consider is a PSU substitution as Bob suggested. You already have a suspicion that PSU capacity may be an issue since you reduced your HD array so buying a new PSU may be a good idea any way and it will certainly tell you if it is a PSU or MB problem.

    Paul

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