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Ask Slashdot: Reliable Powering of ATX Systems?

Posted by Cliff on from the coping-with-soft-power-switches dept.

David Muir Sharnoff writes in with this question: "ATX power supplies don't supply power unless the motherboard says to turn on. Many motherboards do not have a setting of: 'supply power all the time.' This means that ATX systems cannot safely be used a servers. Anyone know of an ATX power supply that ignores signal? " More appropriately: does anyone know of an ATX motherboard/power supply/case combination where powering is similar to AT systems?

10 of 173 comments (clear)

  1. WTX will appear *very* shortly. by Anonymous Coward · · Score: 4


    WTX will replace ATX for server boxes. It appears to be a good spec to me.

    WTX.ORG

  2. ATX specification URL by Anonymous Coward · · Score: 5

    The ATX specification can be found here:

    http://www.teleport.com/~atx/spec/index .htm

    (Boy I hope this message get moderated up.
    That would be keen.)

  3. ASUS P2BF & Intel Nightshade by Eric+Green · · Score: 4

    I know for a fact that the ASUS P2BF has a "AC Power Fail Auto-Restart" BIOS option and the Intel Nightshade has a "Restore Power State" BIOS option that will turn the power on automatically if it was on when AC power was lost (i.e. power was not turned off via the front panel switch).

    --
    Send mail here if you want to reach me.
  4. Mod to keep power on all of the time by gavinhall · · Score: 4

    Posted by el_steevo:

    From the power supply wires coming from the power supply in the case to the MOBO, short the green wire to ground. This will give you power all of the time.

    1. Re:Mod to keep power on all of the time by aressa · · Score: 4

      Make sure you drop a 10kohm resistor in there, or you will reduce the life of the power supply...
      We ran into this same issue with some boxes that we wanted to boot right up when power was applied, soldering gun and a handfull of Radio Shack Resistors later we were golden...

      A

  5. Do it in hardware by Booker · · Score: 5
    Pin 14 on the ATX power supply connector is the "PS-ON" signal. From the ATX spec:
    PS-ON is an active low signal that turns on all of the main power rails including 3.3V, 5V, -5V, 12V, and -12V power rails. When this signal is held high by the PC board or left open circuited, outputs of the power rails should not deliver current and should be held at a zero potential with respect to ground. Power should be delivered to the rails only if the PS-ON signal is held at ground potential. This signal should be held at +5VDC by a pull-up resistor internal to the power supply.
    So, you should be able to hack it together to have that pin permanently grounded, so that the PS is always on. I haven't tried this; I think it should work fine, but don't blame me if your motherboard burns! :-)

    There's also more info on ATX at http://www.teleport.com/~atx/

    1. Re:Do it in hardware by komet · · Score: 5

      We do this with all our servers (medium-size ISP in Europe) and it works without any problems at all.

      Just take a bit of the isolation off the wire of Pin 14 (usually, bit NOT ALWAYS green). There's a GROUND signal on either side of this; take the isolation off that as well. Then solder together and wrap with insulating tape. Works like a charm. The only thing you shouldn't do is tell the mobo to power off; it gets a bit confused then.

      This is where pin 14 is:
      Looking down onto the contacts: (wires on rear)
      v--(plastic tab)
      ===
      + + 0 # 0 + + + + +
      + + + + + + + + + +

      # is pin 14. 0 is ground signal, should be a black wire.

      --
      Any technology which is distinguishable from magic is not sufficiently advanced.
  6. Do it with hardware by SEWilco · · Score: 5

    At hardware and auto parts stores you can get solderless connectors which tap a wire into an existing wire. You can use two of them to add a wire which connects the wires for pin 14 and a neighboring wire. They're usually blue plastic with a metal tab which you push into the two wires. Faster than soldering and can be removed for maintenance.

  7. A couple options by Zachary+DeAquila · · Score: 5

    There're a couple of options

    Some ABIT motherboards can be strapped with a
    jumper between the reset and power switch connectors to make them act in an 'always on'
    fashion like AT motherboards do.

    If you feel like experimenting a bit, you can
    look in electronics parts catalogs for POST
    transistors... these basically act like delayed
    momentary-on relays. One lead goes to +5V,
    the others go to the power-switch jumper.

    --Z

  8. My motherboard is ATX/Server, no problems here... by Vanbo · · Score: 4

    I have a Supermicro P6GDE (Dual PII 400, GX chipset) that has a jumper on the MB to choose, "Bios Power Stater, or Always on..."

    As soon as I through the switch on the back of the powersupply its on, and if that switch is left in the on position then it comes on when the power returns after a black out, etc.

    Note the case is a supermicro ATX750 or something(which is really an Antec Case and Powersupply) and it seems to be designed just for this...

    --
    VANBO