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PC Shuts down. after 1 second


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#1
sahneprinz

sahneprinz

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Hello there! It's my first time here, so please be patient! And pleased to meet you!

I looked around a bit in the forum at first, before posting, but I thought maybe now I should do so.
About the problem: I have a 3 year old PC, and two days ago it started to not pass POST (as I think it is called) i.e. it seems to boot for one second: I can hear the fans, and it shuts down afterwards.
The first time that happened, I opened the case and removed A LOT of dust.
I tried booting, and voila! it worked! (yay)
The day afterwards, it started with the shut down again.
I tried checking the different power supplies: disconnected the HD, and it worked. So I changed the power connector to the HD, and it worked! (yay!)
To check if it was the power connector to the HD, I shut down the pc after some hours, went for a walk and came back again. And again, it only started for one second, and then it shut down. I tried disconnecting everything: HD, DVD drive, Video card. Only the MOBO was connected to power through those two connectors which I do not know the name. (that big one, and that little one with only four pins.) It didn't work. I tried disconnecting the smallest one from the MOBO and tried again. It started up. I shut off everything quickly.

So, after reading around in the internets, I thought maybe it was the PSU. So I went to a store, told them my story, showed them my PSU. They passed it through a tester, and told me it looked fine. But they also told me, that there was nothing connected to the PSU at the time, so it didn't have any strain, so it could malfunction anyway when i connected everything. That they would actually try out a different PSU. And if the PSU isn't the problem, it will most probably be the MOBO. So I took a new PSU back home, fingers crossed, and tried it out. It didn't work.

I think now it has to be the MOBO. What do you think? How should I go about finding a replacement MOBO? mine is a GF7050V-M7 SE.
Do you need any more information?
Thanks in advance!
Sahneprinz
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#2
rshaffer61

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Hello sahneprinz.... Welcome to
GeeksToGo, :D
:D :D

I'm sorry to hear about your issue. We will try to help you resolve this as soon as possible.
  • Please understand we are all volunteers and we are not here all the time.
  • Sometimes it may be a extended amount of time to get back to you. If it has been
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    then.
  • Please do the following and supply the requested information as needed. If you
    don't understand my instructions please ask and I will try to explain them
    clearer for you.
  • Do not attempt any steps unless instructed or ask before to
    make sure they will not cause any further issues.


Lets check the mobo then since that is the most logical choice at this time.

Disconnect everything from the Motherboard except
  • keyboard
  • mouse
  • video output
  • 20+4 powercable
  • 4/8 pin 12v wire both coming from the powersupply,
  • Cpu fan wire
  • power and reset button to the case
  • case speaker
Now you should have NOTHING connected to the motherboard except what was listed above.

The goal here is just to test the mobo:

If the computer still will not boot up the please remove the motherboard from the computer along with the power supply

place the motherboard on a piece of card board larger than the motherboard,

this will eliminate a short from the mobo to the case which could be a possibility

Install the cpu with, 1 stick ram in dimm 1, power supply, case switch and case speaker
Connect ps2 mouse and keyboard along with the monitor
Repeat the above and power on
If the computer now boots into bios you most likely had a case short so make sure when installing the motherboard in the case that you use standoffs,
and they line up with the mounting holes in the motherboard and none of the standoffs touch anything else on the underside of the board.


Thanks to Cbarnard for these instructions
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#3
sahneprinz

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Lets check the mobo then since that is the most logical choice at this time.

Disconnect everything from the Motherboard except

  • keyboard
  • mouse
  • video output
  • 20+4 powercable
  • 4/8 pin 12v wire both coming from the powersupply,
  • Cpu fan wire
  • power and reset button to the case
  • case speaker
Now you should have NOTHING connected to the motherboard except what was listed above.

The goal here is just to test the mobo:


I did this, but to no avail. I'll try to take the mobo out afterwards, when I got some more time, but I don't think it is a shortcut, since it starts up for one second.

some more info: I checked the mobo guide, and it says the four pin power connector is for powering up the cpu. So, if disconnecting the four pin makes the pc "start", since all fans work for longer time, does that mean the cpu is cooked?

thx, I'll try that with the cardboard later.
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#4
sahneprinz

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I just put the motherboard on a cardboard, just as you said, but it also only started for one second and then shut off.
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#5
rshaffer61

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So, if disconnecting the four pin makes the pc "start", since all fans work for longer time, does that mean the cpu is cooked?

I would say that is a good indication then of a cpu failure.
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#6
sahneprinz

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So I don't have to change the mobo; i have to change only the cpu?
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#7
rshaffer61

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I would say yes. If you disconnected the power from the cpu or what seems to be the fan you are describing above and it works it may be the fan if it boots.
The cpu is powered when it is inserted into the lockdown connection on the mobo. So if it powers up still there then the issue may be the fan.
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#8
sahneprinz

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I guess it is the CPU then. The cable I disconnected was the 4 pin CPU main power cable
Posted Image
that one (it's not my board, I took it from playtool.com)
In my mobo installation sheet it says, referring to the 4 pin main power connector, and I quote: "JATXPWR2, the 4-pin ATX 12V power connection, is used to provide power to the CPU. Align the pins to the connector and pres firmly until seated."
So I understand, with my almost unexistant pc skills, that the 4 pin main power cable works in this mobo solely as power provider for the CPU. Disconnecting it still makes the CPU fan work, since it is connected somewhere else. It works perfectly. But it is a PC without an active CPU in that situation.
Is this plausible?
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#9
rshaffer61

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Yes this is the secondary power connector for the motherboard.
Disconnecting it will have no affect on the cpu fan but only the mobo. Most likely the mobo will not boot at all once it is disconnected.
Without a cpu the system will not boot at all.
As I see it right now it looks like one of two possible issues.
Bad motherboard
Bad CPU.
It also could be a combination of the two and thus both would have to be replaced. If you decide to take this route it would be time to think about a nice upgraded mobo and cpu.
I have taken the libery of looking at TigerDirect and found the same socket mobo with a cpu HERE.
Price ranges from 110.00 to 185.00 USD which doesn't include the shipping.
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#10
sahneprinz

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What happens if I buy a new CPU first, and attach it to a "faulty" mobo? Can I fry the new CPU that way? Should I directly buy a new combo CPU+mobo? I'm inclined to think it is a bad CPU, since the PC shuts off when power is supplied to the CPU through the 4 pin secondary main power connector.
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#11
rshaffer61

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What happens if I buy a new CPU first, and attach it to a "faulty" mobo? Can I fry the new CPU that way?

If the mobo is the issue then yes it can fry the new cpu.

Should I directly buy a new combo CPU+mobo? I'm inclined to think it is a bad CPU, since the PC shuts off when power is supplied to the CPU through the 4 pin secondary main power connector.

That is a option you can take and it very well may resolve the issue. If the system starts up then you will know for sure it was the cpu. If not then you will have to replace the mobo.
I was suggesting the combo as normally it is cheaper to buy them together then at different times.
Also replacing both would guarantee the issue would be resolved unless it is another piece of hard ware which at this time I am seeing no signs of it.
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#12
sahneprinz

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Is there any way I can make sure which one of the two is actually fried?
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#13
rshaffer61

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Not without replacing one or the other.
You can take everything out and bench test the mobo, memory, cpu and see if it posts with just that.

Disconnect everything from the Motherboard except
  • keyboard
  • mouse
  • video output
  • 20+4 powercable
  • 4/8 pin 12v wire both coming from the powersupply,
  • Cpu fan wire
  • power and reset button to the case
  • case speaker
Now you should have NOTHING connected to the motherboard except what was listed above.

The goal here is just to test the mobo:

If the computer still will not boot up the please remove the motherboard from the computer along with the power supply

place the motherboard on a piece of card board larger than the motherboard,

this will eliminate a short from the mobo to the case which could be a possibility

Install the cpu with, 1 stick ram in dimm 1, power supply, case switch and case speaker
Connect ps2 mouse and keyboard along with the monitor
Repeat the above and power on
If the computer now boots into bios you most likely had a case short so make sure when installing the motherboard in the case that you use standoffs,
and they line up with the mounting holes in the motherboard and none of the standoffs touch anything else on the underside of the board.


Thanks to Cbarnard for these instructions
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#14
sahneprinz

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I have done that already, like you told me. Thank you very much rshaffer61, you've been very helpful! I'll go to a store now and get me a mobo and a CPU.
Thx again!
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#15
rshaffer61

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Not a problem and I apologize as I have been busy here outside and just now got back to the computer. Please let me know if everything boots up once the new mobo and cpu are installed.
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