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Computer boots for 1 second then turns off

Hi everyone :hello:


When I try to start my computer by pressing the power button, the first time it starts and stays on for one second only and then switches off, it does not even reach the POST screen... it switches off within a second after it starts. And when I press the power button again in this state it does not start at all... not even for one second like it did the first time. Then I have to switch off the main power supply to the computer and switch it on again before the power button works but again the computer starts for may be one second then switches off. If the main power supply is kept on and the power button is pressed again then it does not work... then again I have to switch off the power supply and switch it on again to make the power button of the computer work again. This way I have to switch off the power supply and switch it on and then press the power button of the computer and after several such attempts while the computer stays on for one second and then stops, it finally boots up completely. I have noticed that when it finally boots it makes several clicking noises before it starts.

I have replaced the CMOS batteries but that did not seem to help. I have also replaced the cable, plugged it into another power supply but that did not help either. I have also disconnected the cable running from the power button to the mobo and tried starting the computer by briefly touching the pins on the mobo With a metallic object but it gave the same problem as before. So the fault is not with the power button either.


What could be the problem? Can a bad capacitor cause this problem? I think I have noticed a minute quantity of some sort of brown powder over one of the capacitors of the motherboard. I am not sure if the capacitor is damaged though.

Also, is there any software application to diagnose this problem?


Please help me.

Thanks in advance. :)
8 answers Last reply Best Answer
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  1. Unfortunatly there is no software application to diagnose this.
    TBH youve basically answered your own question; your mobo is obviously your issue.

    Narrowing down the cause of the issue is going to be rather tedious, the clicking noise is coming from an overcharging capacitor.

    In my opinion, dont even bother trying to fix it and just go ahead and grab a new mobo. It is likely the the capacitor with brown powder which is the issue but the real question is what cause that capacitor to overload and that is where the fun really begins.

    In summary its about time to get your wallet out and get yourself a Christmas prezzy.

    Thanks
    Sig
  2. check that capacitor for cracks or bumps
  3. Sigh. :pfff:

    Bad caps, although they still happen, are not the problem they were 5 years ago.

    Before you go out and replace the motherboard, you should do some serious troubleshooting first.

    "When I try to start my computer by pressing the power button, the first time it starts and stays on for one second only and then switches off, it does not even reach the POST screen... it switches off within a second after it starts. And when I press the power button again in this state it does not start at all... not even for one second like it did the first time. Then I have to switch off the main power supply to the computer and switch it on again before the power button works but again the computer starts for may be one second then switches off."

    This could very well be caused by a bad PSU.

    When you are asking for help, always start off with the system specifications.

    Work systematically through our standard checklist and troubleshooting thread:
    http://www.tomshardware.com/forum/261145-31-read-posting-boot-problems
    I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

    If not, continue.
    The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

    I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

    Breadboard - that will help isolate any kind of case problem you might have.
    http://www.tomshardware.com/forum/262730-31-breadboarding

    Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

    Make sure you plug the CPU power cable in. The system will not boot without it.

    I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

    You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

    If no beeps:

    Check for line power at the PSU input. Extension cords, power strips, and power cords do fail.

    If you have power and no beeps, suspect components in likely order are PSU, motherboard, and CPU. CPU failures are pretty rare.

    Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

    At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

    The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

    You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
    http://www.youtube.com/watch?v=5FWXgQSokF4&feature=youtube_gdata

    A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

    This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

    If the system beeps:
    If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

    Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

    Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
    At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

    Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
  4. i had a similar problem. it was down to an incompatible psu. there was actualy nothing wrong with my system but it wouldnt boot al att.. id turn it on and see the L.E.Ds light up and then they would go off. i hit the power button again and nothing... turn all the power off wait 5 mins hit the power and it would come on again for a half second then off again.
    the guy in the shop said something about the phase being wrong for the motherboard/cpu and i should try a different brand...

    so i recommend you try and borrow a psu off a m8 and test yours in his setup to see if you get similar results.
  5. Thanks everyone for your replies. :)

    @jsc thank you again.

    Sorry... I forgot to mention the system specifications earlier. Its P4 3.06 GHz processor, Mercury PVM7 Version3.5 motherboard with VIA chipset, 1 GB RAM, and 2x160 GB IDE HDD, 1 TB SATA hard disk. ( so I have three HDD), LG DVD Writer.


    This time I have observed that when I disconnected the power cables running to any of the three HDD, the computer starts normally however if I connect all the three HDD at a time then the problem shows again. This configuration was working perfectly fine until this problem showed up. Could it be a bad PSU as you have suggested?

    Thanks in advance.
  6. Best answer
    as its an old pc its psu is likely to be the original 350v model and as you add more it becomes unstable... sounds like your at the maximum output of the psu...
    you should either remove some of the ide drives, this will save about 20w per hdd but is a short term fix. it may allow you to use the pc without issue but its more likely it will allow you to use it till the problem starts showing up again but then the psu will be on its last legs. and may take the rest of the pc with it..

    so if you can afford it. get a replacement 400-500w for 45-50bux/quid. nothing 2 expensive because they system doesnt warrant any more money spent on it because of its age.
  7. @Hexit & jsc

    thanks for your help... it was a bad PSU. I got it replaced and the problem is solved. thank you everyone for your help.
  8. Best answer selected by angela_s.
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