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Mobo short out problem?

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  • Mobo short out problem?

    My motherboard hates my case. Outside of it, it'll work fine. Computer boots to Windows, runs normally. But if I put it in the case, the system will freak out and either fail to POST or freeze up or intiate multiple successive reboots and then freeze.

    My system:

    Antec Sonata II case, 500W SmartPower PSU
    MSI K8N neo platinum
    AMD 3400+ socket 754
    2x 512mb kingston DDR 400 SDRAM
    ATI Radeon 9800 AGP (have also tried with an nVidia 6800GT, no difference)

    The case has 5 copper spacers screwed in, currently. I have tried up to 9 (the mobo's maximum), making sure that there's a screw for every spacer. I have also tried using insulating washers under the screw tops, to be doubly safe. The problem's existed for a long time now, so I've even gone so far as to coat the motherboard-side wall of the case with electrical tape. I've also tried nylon screws.

    What happens is: I screw in the mobo. I hook up all the PSU and case wires. (Case is on its side at this point) I put in the video card and connect it to the mobo. I start the system. It POSTs. It runs for a little while (say, a few seconds to a minute), and then freezes. If the hard drive's connected, usually on the first try it'll get all the way through the windows loading screen, and then it'll reboot. Then it'll get to the loading screen again (or not quite) and freeze. This happens without fail.

    Also, if I move the case off of its side, so it's right-side-up, there's about a 90% chance it'll fail to post, with a series of long, repeating beeps. (The other 10% of the time it behaves as it did when it was on its side.) I've done all the usual fail-to-post things -- reseated memory and other cards, etc, but they don't help. The only way to get the system to POST is to turn it off, lay the case on its side (motherboard side resting on the ground), and turn it back on.

    There are no loose screws or other metal pieces sliding around inside the case. It is not dusty. I do not know how the motherboard could possibly be touching the case, and don't see any points of contact from where I'm sitting. I also don't know why it would be more liable to have problems in an upright position, where gravity would not be pushing the mobo against the case. Is there something else this could be besides a short circuit problem, or some potential source of a short circuit I wouldn't have checked?

    Thanks in advance for whatever help you can offer.

  • #2
    Re: Mobo short out problem?

    Does that power supply have a grounding strap? If so then make sure to attach it to some grounded location in your enclosure. If not, then remove the power supply and set it on something (like a box) that has no metal in it. While rare, it could be that the PSU is grounding out and not the mainboard.

    Just a thought.
    Old age and treachery will overcome youth and skill
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    • #3
      Re: Mobo short out problem?

      Thank you for the quick response. I will give that a try.


      • #4
        Re: Mobo short out problem?

        No luck. Same problem. Any other ideas?


        • #5
          Re: Mobo short out problem?

          All right, good news is, it's probably not a short-out. Bad news is, my system insists on initiating reboots very frequently - like within 30 seconds of booting up - both inside and outside the case now. As before, the reboots go for awhile and then the computer just up and freezes. What are my likely causes?


          • #6
            Re: Mobo short out problem?

            I've seen a similliar case once before, to get that system running we packed paper under one corner of the motherboard and then it worked. (this was a Pentium - so its a while ago)

            that may not be related but check mboard for dry solder, cracks

            I'd try
            removing all non esentiall hardware, ie cdroms network cards, just leave enough to boot.

            could be faulty PSU, ram, mboard, video card (rarer).

            use your nose and have a good sniff, you'll know if you find something that way.

            my guess is its the PSU, buy a new case and try that.