Computer won't even start to post, constantly restarts after 10 secs

Originally I posted this in the Motherboard/Gigabyte forum. Because I thought it was probably a motherboard fault.

But I decided to test the power supply first. I used to know my way around electronic thingies, but that was twenty plus years ago. I looked up on the internet, how to test a power supply and followed the steps.

I removed the power supply connectors to the motherboard. I shorted out the green and black wire on the 24 pin connector, to start the power supply. I then tried to test a black/yellow combination for twelve volts, as pictured in two different sets of instructions, I’ve looked at. I‘ve got a multimeter set on a 20 VDC scale. The power supply immediately shuts off, like a circuit breaker blowing. I turn the power supply switch off then on, and the connected fans start to spin again.

Now, am I just shorting this sucker out, which certainly seems to be the case to me? As I said, I’m following instructions found on the internet. Or is this an indication that the power supply is bad?

The original problem, that I’m trying to solve.

My computer will not freaking work. I press the power on button. It does not make any calls to or attempt to access: hard drive, optical or floppy disk drive. Nothing appears on the monitor. Fans start to spin. Ten seconds later the computer turns itself off. About 1 minute later it tries to restart itself. This cycle repeats, until I turn the power supply off.

I built this system in November of 2007.
Intel E6750
Crucial Ballistix DDR2 800 PC26400
Samsung Hard Drive and Optical
Sony Floppy
Antec Earthwatts 430 watt power supply

What I’ve done:

I’ve verified power going into the power supply. I’ve reseated all connectors, cards and memory except the CPU. I’ve tried bootable disks in the optical and floppy drives. I’ve tried clearing the CMOS. I’ve tried running the computer without drives, without memory and without the video card in all different ways. The same things happens. I’ve pulled the motherboard reset the wire, I thought it might have been stuck closed. I put up my shotgun against the computer and tried threatening it.

I am down to three options.
Bad power supply
Bad Motherboard

I plan on trying the power supply first. Does anyone have and advice or suggestions?


What I've done, since. I've connected a pc speaker to the MB, all it does is give me one beep when I first press the power on button. It is silent there after. I've also removed and checked the motherboard for shorts, nothing.
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  1. How many connectors does you multimeter have, although you set it to 20VDC (which is correct), if you connected it to the point for testing currents then it would do that. A lot of them will look like this:
    In which case you connect as shown in this picture, and don't connect the red wire to the 10ADC.

    If that is not the case then there is either something wrong with the multimeter or the power supply.
  2. That's what I was doing wrong thanks. Power supply testing ok. Contacted Gigabyte tech support, they are prettty certain problem is mother board or bios.
  3. It could easily be the mobo, I have had my share of GA insanity, but i still buy them.

    You said you pulled the mobo. By that did you mean you did a minimal install on cardboard, or pulled and replaced?

    I have a feeling that it might be install. Of course If I had made a thread about some of the insanity that I dealt with I would get the same questions and it wasn't install in those cases.

    Strip it and see how it POSTs.

    Build it on cardboard with one stick and see how it goes.

    It may be a flaky mobo, certainly not unheard of.

    At least come back and give me an update.
  4. Do what Zorg suggests - except go even farther. Take the motherboard out of the case and place it on an insulating surface. Make sure that both PSU power connectors (main 24 pin and 4/8 pin CPU power) are installed.

    Pull everything except the CPU and HSF. Boot. You should hear a series of long single beeps indicating memory problems. Silence here indicates, in probable order, a bad PSU, motherboard, or CPU - or a bad installation where something is shorting and shutting down the PSU.

    If you get the long beeps, add a stick of RAM. Boot. The beep pattern should change to one long and two or three short beeps. Silence indicates that the RAM is shorting out the PSU. Long single beeps indicates that the BIOS does not recognize the presence of the RAM.

    If you get the one long and two or three short beeps, install the video card and any needed power cables. If the video card is good, the system should successfully POST (one short beep, usually).

    Note - a PSU with inadequate 12 volt output will also cause this step to fail.

    Another note - you do not need drives or a keyboard to get this far.

    If you successfully POST, start plugging in the rest of the components, one at a time.

    Building the computer outside the case is called "breadboarding" (from the 1920's days of homebuilt radios). I use an insulated cutting board. I always breadboard a new build. It lets me test the components before I go through all the work of installing them in a case.
  5. Don't forget, you won't hear any beeps unless you have a speaker attached to the mobo front panel header speaker out.
  6. start here

    you must go though this guide first before we can help u let us know if you found ur problem or still need help after trying all the items in it. (I got in trouble for helping someone else for this with out sending them though the guide first)
    we will assume you checked all these items so really go though the list

    as a note any no boot on a system guys your suppose to tell them to go through this list before starting a long thread like this. I got in trouble by a mod for this guys
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