Suspicious problem.

By r00tman ยท 9 replies
Sep 19, 2005
  1. This happend when i started my computer, it tried to cold start going off and on, but finally started, everything seemed to work. After 3 days i turned the computer off. Now when i try to start it nothing happens, although there is a green lamp on the motherboard glowing.

    I pulled everything except processor from the motherboard, and plugged in. outlet power, Nothing, well it should not happend anything as the computer dont start so motherboard isnt running any routines?

    Anyway i did try with a voltmeter on the pin connector from the psu but it showed nothing? I also tried voltmeter on molex nothing there either. Maybe because the computer isnt running at all and the psu isnt started? but it should output something? as the green light is glowing on motherboard.

    Appreciate any feedback.
  2. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    Hello and welcome to Techspot.

    It sounds to me like your psu has died.

    Replace it with a known working psu. Hopefully that will solve your problem.

    If not, please post back.

    Regards Howard :wave: :wave:
  3. Merc14

    Merc14 TS Rookie Posts: 171

    Put in the RAM and the videocard and see if you can get into BIOS. Don't plug in any drives.
  4. r00tman

    r00tman TS Rookie Topic Starter

    Thanks for reply, yes ive tested running with every possible configuration, even plugged out CPU once, nothing. I have ordered a new PSU. I did one maybe fatal misstake though i left the current PSU plugged in, and when i got back the fan on psu runned, but not the processor fan, the cooling structure above CPU was lava hot.

    This was even as the system was dead, except the led on motherboard. And if PSU is bad i dunno how it can put out enough voltage to make CPU that hot? Voltmeter showed zero, perhaps after a while something short circuit and the psu started putting out power.

    As it takes two different pins to short circuit starting the psu power output, wich i think normally happen when you use the power button? , its a dell btw so nothing is standard, power button is connected through two special chips before reaching the actual motherboard. First chip is the actual power button attached to, then you have the usb audio headphones out, wich also the soundcard is connected to then finally a wire to the motherboard.

    But i still dont understand how PSU can be bad if the computer was running before turn off, something must have broken the moment i turned off the computer. Ill just have to wait and see with the new PSU, i dont have any warranty left either, but its fairly new as i got a brand new comp off warranty just before the warranty runned out :).

  5. r00tman

    r00tman TS Rookie Topic Starter

    I bought a new PSU antec 480 w, this time the fans turned on. MB led lit, however no sounds, no boot. I could turn off the psu with the power button on front chassi. So i guess either pcu or motherboard is gone then.
  6. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    Sorry to hear the new psu hasn`t solved your problems.

    Look at the mobo`s capacitors. Are any of them domed, or leaking?

    Look HERE for a pictorial explanation.

    Take a look HERE just for interest.

    Regards Howard :cool:
  7. Merc14

    Merc14 TS Rookie Posts: 171

    If the mobo looks sound then try the following:
    You are going to have to do a barebones setup and test each component. This will read a lot harder than it actually is. The initial procedure takes only around 10-15 minutes. The follow on troubleshooting may take a lot longer though. Also, please do not skip steps. Do everything in order and as listed or your troubleshooting will be flawed.

    Caution: Please remember that turning a PC off does not mean there is no power going through it. Modern systems maintain a trickle of power to keep the standby functions running. You either have to turn off the switch on the Power Supply Unit (PSU) itself or unplug the system from the wall. Unplugging is best. If you have a LED on the mobo that is lighted all the time. make sure it is out before proceeding. Also, be aware of static. Make sure you wear and ESD strap or discharge yourself on a steel part of the case before touching anything inside.

    First, unplug the PC from the wall and then open it up. Disconnect all the drives (floppy, CDROM, DVD etc.)from the motherboard (mobo) and also disconnect your Hard Drive(s) from the mobo. Do not leave the hard drives connected. The system will boot into BIOS just fine with no hard drive attached. Unplug the power from all those drives you disconnected from the mobo. Remember to disconnect the front panel firewire and/or USB ports.

    Next, remove all the RAM, except for one stick, from the mobo. Some mobos are very picky about where the RAM needs to be placed so make sure the one stick of RAM is in the correct slot as per your manual.

    Now you are stripped down to a barebones system. The PSU, the mobo itself, 1 stick of RAM, the CPU/HSF and video card. Reset your CMOS/BIOS while the system is stripped down, unplugged and open. You do this by removing the battery and then moving a jumper near the battery around. Usually there are a set of three pins with two covered by a jumper. You move the jumper from pins 1&2 to pins 2&3 and let it set for a few minutes then reset the jumper to pins 1&2 and replace the battery. CMOS and BIOS will be back at default settings after doing this.

    Now check that everything is seated correctly, both the 4 pin and 20 or 24 pin power is connected and secure and if so then plug the PC back into the wall and make sure that any LEDs that should be lighted on the mobo are lighted. If all is still well then turn it on. Hopefully she boots right back into BIOS.

    If you get back into BIOS you can start troubleshooting by turning the PC off and unplugging it and reconnecting peripherals one at a time. The idea here is to connect and reboot until something hangs your system up This presumably is the bad piece of gear.

    If you cant get into BIOS and have the same problem as before then you know it is either the PSU, the RAM, the CPU, the mobo itself or the video card. Change out each these until you get into BIOS. I would start at the PSU as it is usually the guilty party in a situation like this and is also easy to change in and out you are down to just 2 plugs now remember). Next up would be the video card and/or RAM and if still no luck then things get hard as you now have to consider either the CPU or the mobo.

    Good luck and happy hunting.
  8. r00tman

    r00tman TS Rookie Topic Starter


    There is no way to get into bios, im thinking of just letting it be and build a new computer. A light pressure on the heatsink turns the psu off also. But i was thinking just because you turn on the psu doesnt mean it just magically starts, isnt there a start routine involved with the power button. Its connected first to its own chip then via cable to another chip (usb,headphones) and finally cable to the mb. Maybe something is burned on route to the mb from the power button. But im 90% its the cpu or mb now, memory and graphic card ive been able to test they are ok.
  9. Vigilante

    Vigilante TechSpot Paladin Posts: 1,666

    It's a Dell, you said, and yes, nothing is standard. I wouldn't be surprised if your new generic power supply finished the job. As Dell often rewires their power supply a different way. Just for fun, compare the mobo power plug on the old power supply to your new one, if the colors are not all the same, in the same plug, you can't use the new PS anyway.

    If your CPU heats up, it is either working (regardless if you have video), or there is voltage problem and the system is just cooking it.

    Being that you have stripped the PC, and swapped the PS. And being that your CPU could cook a burger. And being that it is a Dell. And assuming thus far that the problem must be in the CPU/mobo/video department. If you are even half-way thinking of getting a new system, I would encourage to do so. Cut your losses.

    This time around, get a PC that supports standards. Build your own, or buy a custom.
  10. r00tman

    r00tman TS Rookie Topic Starter

    The antec truepower 480 w psu dont have any compability problems with the modern systems from dell, in this case a dimension 8300. The wires are the same, the only problem is the chassi that you would have to make a hole in to fit the on/off and power outage on psu. But what im curious about is if its such a simple problem that something shortcircuit in the chip the power button is connected to so that the mb dont get the ps on signal, then simply switching the chip would make things work. Then again i would probably build a new computer faster than getting a new power button system. Also i think its a longshot, but im sure gonna find out when i have a second system to try things with ( Or not :=), ill just leave the oem stuff alone).
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