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I'm not able to switch on my PC :-((

Discussion in 'Hardware' started by Oliver S, Nov 15, 2003.

  1. Oliver S

    Oliver S Guest

    Hi guys!

    Hopefully you have an idea of what's going on. Fact is – I'm currently
    not able to switch my PC on.

    First of all my components:
    Case: Aspire X-Superalien
    Motherboard: P4P800-D
    CPU: P4, 2.8GHz, 800 FSB
    Ram: Kingston 2xDDR 512MB-400
    Video: MSI FX5900-VDT
    Sound: Soundblaster Audigy Gamer
    OS: Microsoft XP Pro

    Now the history:
    A couple days ago I finished building my PC and installing all the
    drivers. Everything work fine. Today I just checked my system again
    and detected that I forgot to install the Ethernet driver and RAID
    driver for the motherboard. After that I rebooted and the PC was still
    running smooth. I turned my PC off and tried to start it a couple our
    later again. And – nothing happened. I checked already the wiring and
    also unplugged the PC, but this didn't fix it. Currently I guess my
    motherboard is damaged… By the way - the Power LED on the motherboard
    is on!

    Oliver S, Nov 15, 2003
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  2. Oliver S

    Oliver S Guest

    Here an update:

    I checked the PSU and I have a 5V signal on +5VSB and PS_ON.
    Also I tested the reset switch and the power switch. Both are working
    fine (0 Ohm when pressed). After that I unplugged everything - video
    card, sound card, floppy, HDD and my case fans. I took the CPU out and
    also the memory and put them in again. Also I reset my motherboard.

    The result was - still nothing happens when I try to switch on my PC.
    I also tried it without CPU and memory with the same result.

    Does this mean my motherboard is dead?


    Oliver S, Nov 15, 2003
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  3. Oliver S

    Harry Guest


    By the sounds of it, there must be something wrong with your
    motherboard. By the way did you check the BIOS?
    Harry, Nov 15, 2003
  4. Oliver S

    Oliver S Guest

    I'm not able the check the BIOS since it doesn't boot up, but I reset
    the settings.

    Does somebody know a way to test the PSU? Can I somehow fake the
    feedback signals to activate the +12V?


    Oliver S, Nov 16, 2003
  5. Oliver S

    ray Guest

    if ur not getting error codes without ur ram n g-card then ur mobo is
    at fault or the spply to it as fault (but u say the mobo LED dosnt
    glow??) well it woudnt hurt to test it on a working PSU
    ray, Nov 16, 2003
  6. Oliver S

    Oliver S Guest

    Ok guys here some notes to that an I think I found the problem - thx
    to luke313

    According to http://www.tkpower.com/pdf/TK350AA-PFC.pdf : When PWR_ON
    is pulled to TTL low, the power
    supply should turn on the five main DC output rails: +12VDC, +5VDC,
    +3.3VDC, -5VDC, and -12VDC.
    After that I should be able to check the PWR_OK:
    PWR_OK is a "power good" signal. It should be asserted high by the
    power supply to indicate that the +5VDC and +3.3VDC outputs are above
    the undervoltage thresholds ... and that sufficient mains energy is
    stored by the converter to guarantee continuous power operation ...
    Conversely, PWR_OK should be deasserted to a low state when either the
    +5VDC or the +3.3VDC output voltages falls below the undervoltage
    threshold, or when mains power has been removed for a time
    sufficiently long such that power supply operation cannot be
    guaranteed beyond the hold-up time.

    Something to check for me

    A replay on that was:


    There is a test you can do to find out whether it is your psu that has
    blown or your motherboard. Unplug all connectors and then look at the
    motherboard power connector (the long thin one) and at the 20 wires
    connected to it. The one side of wires should have this order of

    11 orange
    12 blue
    13 black
    14 green
    15 black
    16 black
    17 black
    18 white
    19 red
    20 red

    Some of these colours may be slightly different depending on psu. Now
    attach one of the molex connectors to a spare fan, and get a paper
    clip/staple or something to short out two of the wires in the
    motherboard connector. Once you have got a metal wire/object, short
    out the 14th and 15th wires as these are the wires that control the
    power output. If you then plug the psu into the mains the fan should
    immediately power up. If it doesn't you now know your psu is b0rked
    and you need to test your motherboard with a different one.
    Oliver S, Nov 17, 2003
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