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PC Not Booting Until a Different Phase is Used?

Posted by Cliff on from the mysteries-of-the-server-room dept.

2by4 asks: "I run at IT Dept for a small firm, our network room houses production & development servers. Some machines are plugged straight into a strip with no UPS. Here is the Mystery Problem: When the power glitches, the strip machines go down, and some of these machine WILL NOT come up again until I switch them to a new outlet. Once this happens, I can put them back on the original outlet and they will work. Unplugging & replugging on same outlet is not enough. I have seen this on at least 5 machines so far, with independent confirmation. We can narrow the 'fix' to plugging into an outlet of a different phase (there are 3 separate 120v phases powering the room). The symptoms vary from no powerup, to frozen at the BIOS (depends on motherboard make), etc, but consistently, switching to a new phase fixes them. I tried the 'unplug-wait-&-replug' cycle, to no avail. Using a new outlet w/ a different phase is the only solution. Any theories? I assume the new phase is causing something to 'reset', but what? I can provide more details, but I am wondering if anyone has seen this before? I am completely and absolutely stumped. Our power is healthy, lightly loaded, evenly distributed and the power strips are new. I know I should have at least a simple UPS, but this mystery is causing me to lose sleep."

4 of 130 comments (clear)

  1. Hmm by pclminion · · Score: 5, Insightful
    Have you tried shorting the two power pins of the power plug together? Just tap'em simultaneously with a screwdriver. Maybe a capacitor inside the power supply is charged up and somehow it's blocking the flow on a different phase. If so, it's crappy engineering.

    Obviously, I mean that you should do this with the plug UNPLUGGED.

  2. Are you sure your power is all the way recovered? by argStyopa · · Score: 4, Insightful

    You mention when your power 'glitches'...brownout or blackout or spike?
    We are a light industrial building in a heavy industrial park, and I swear the power goes glitchy 2-3 times per year.

    We'll get brownout and blackouts, and when the power comes back it SEEMS like it's on, but only 2 of the 3 phases of the A/C actually comes up, meaning (depending on how it's wired at the *circuit box*) some circuits are dead, some are full, and some are semi-brownout (our flourescent ballasts LOVE that half-state.....not).

    That third phase sometimes doesn't come back up for hours.

    I have no idea if this is of any help, that electrical stuff is arcana to me, I'm just reporting what we've discovered.

    --
    -Styopa
  3. Re:Check the Neutral To Ground by sakshale · · Score: 4, Insightful
    SHORT RESPONSE: Have a licensed electrician check out your circuits.
    Amen!

    I actually worked on a system where printer interfaces were burning up because an electrician had reversed neutral and ground in the outlet where the printer was plugged in. There was enough of a difference between neutral and ground to damage the interface of the computer.
    --
    For every problem there is a solution that is simple, obvious and wrong.
  4. Sounds like it could be a grounding problem by relifram66 · · Score: 4, Insightful

    This sounds like it could be a ground problem. I'd check (if you have the capability) the hot-to-ground and the hot-to-neutral with an oscilliscope on the effected outlet. Barring that you can check it with a multimeter, you may find that the neutral or the ground is inductively coupled to a hot phase.

    Some other things to check:

    The continuity between the outlet and the electrical box (all three wires).

    That your grounding rod is correct for the type of soil in you area.

    A different power supply.

    Also, like a previous poster noted, try shorting the input to the power supply (when it is unplugged), that may give you a temporary fix.