Computer doesn't turn on, but mobo LED light on

By ajmac88
Jan 7, 2007
  1. hey,
    When i went to bed my computer was working fine. but when i woke up (8 hours later or so), When i press the power button nothing happens, not even a choke to try and start up. The weid thing is that when i turn on the rear power switch, the motherboard green LED is on. So im not sure if this is consistent with PSU failure? I would have that PSU failure for sure but now im not certain.
    i have tried:
    Using a known good power socket.
    switching the power and reset buttons on the motherboard to see if it was the siwtch
    Short circuiting the on switch on the motherboard.
    When i unplug the motherboard power cable from PSU, the green LED turns off, when i plug it back in it turns back on.

    Does anyone know if its a PSU problem or somethign easier? Because it's really throwing me off. I think i have to be getting power, since the mobo LED is on.
  2. nismo91

    nismo91 TS Evangelist Posts: 899   +15

    Hello and welcome to techspot.

    I'm not good at all when it comes to this case, but coincidentally, i have the same issue last year.So i decided to write some possible reasons :
    1. PSU failure (+12V A rail is too low)
    2. Capacitors leaked
    3. Heatsink and thermal gel not installed properly
    4. Few drives problem such as HDD or optical drive
    5. short circuited cables inside the case.

    So far, when this problem happens to me, i could not turn on the PC whenever the HDD is attached. But when i unattach it, the computer would on.
    Or another issue, i have a fan in the case which i have not installed yet. Accidentally, when i move it with a pincer to the correct position, the metal parts of the fan get in contact with the CPU case. Straight after that my computer turned off, BUT the CPU LED is on.

    Well, let's find out more about your computer, can you give your system specs here?
  3. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,689   +395

    A majority of the times this would be a Power Supply issue. That little green light doesn't really tell you anything, just tells you you are getting power down 1 segment of that power supply.

    Unplug the thing, open it up, reset your cmos, hit power a few times, put cmos jumper back where it should be, plug it in, power on. If it doesn't work, look over your motherboard to make sure nothing is obviously blown, replace PSU.

    Also I've seen this work twice (but it was likely a concidence with something else), while the comp is unplugged flip the Voltage switch on the power supply to 230 or 115 (different from where it was) then flip it back before plugging the thing back in.
  4. raybay

    raybay TS Evangelist Posts: 7,241   +9

    It can be a power supply, motherboard failure, or cpu failure. There is a nifty, cheap power supply tester for about $10 at most computer parts stores such as CompUSA. It tests each rail, quickly. It is not great for more intensive tests such as falling amperage on the 12V rail, but good for what you need to know.
    Otherwise, trade out the power supply with another for the test.
    The symptom you describe is typical of the failures in 23 different eMachines models, several Compaq 5000 series motherboards, and the lower end Dell Dimensions 2100, 2200, 2250, 2300, 2400, and 3000... and many other budget computers. When that happens in these, the computer is a goner.
  5. ajmac88

    ajmac88 TS Rookie Topic Starter

    Mobo: K8N e-deluxe
    CPU: amd64 3200+
    vid card: ATI 9800 pro 256mb
    ram: 2gig ddr400
    HDD: seagate 120gig SATA

    Theres my specs, i'll try some of those ideas soon and then repost.
  6. Dieselsplash

    Dieselsplash TS Rookie


    IDk what to do
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