computer starts for a few secondsand then shuts down

[rookie1010]

hello,

i have a 4 year old desktop which uses a gigabyte 81875 ultra and runs a p4-2.2 ghz. Today when i came back home, i discovered that the pc had shut itself down(i had been onholiday till yesterday and had only turned on the pc in the morning with no problems)
i tried to turn it on. the pc turns on for a few seconds shows a part of the boot up(runs through the memory test) and turns off.
i noticed that the ram led light remains on. and if i try to start the pc by pressing the power button, the pc wont start, but if i keep the power button pressed, i can turn of the ram led and then try to start the pc again. the pc starts up again for the few seconds.

can you guys please help?

 

[phaxmohdem]

Unplug the PC from the wall for a minute or two to give the PSU capacitors time to fully discharge, then try again. Some things off the top of my head that could help..

- Use the CMOS clear jumper on the motherboard.. set it to clear... turn on the power for a bit, turn off the power again, then replace the jumper to its normal setting, and see if it boots
- Re-seat the CPU and the RAM, making sure no dust or other foreign objects are present
- Re-seat any cards you may have installed (video, sound, lan, etc)

If that does not work, I'd try unplugging my hard drive(s) and optical drive(s), see if it will stay on without those, then one by one plug them back in to see if one of those are the culprit. Try a different PSU, to see if that is the problem... if not I'd wager something went awry with the motherboard.

 

[myocardia]

Originally posted by: phaxmohdem
- Use the CMOS clear jumper on the motherboard.. set it to clear... turn on the power for a bit, turn off the power again, then replace the jumper to its normal setting, and see if it boots

Do NOT do this. You don't supply power to something with it intentionally shorted, which is what moving the CMOS jumper to the Clear position does-- it shorts out the CMOS chip. The rest of your post is very good advice, though.

 

[mpilchfamily]

I've delt with problems like this before and have ran into 2 differnt things that cause it.

One is a bad PSU and the other is a bad motherboard. In the case of the mtherboard some of the capacitors on the board had gawn bad and where buldging. So check the board to see if you have any buldging or leaking capacitors. With the PSU it was the same sort of thing. The unit had leaking capacitors. So which ever one is the problem it needs to be replaced.

With the motherboard one i tired to replace the caps but there where other damages to the system. On that system the motherboard was damaged due to the system being powered down wrong. The guy had the system plugged into a outlet that was controlled by a light switch. So the switch often was used to power down the system thus causing electrical surges damaging the board.

 

[rookie1010]

thanks or the replies,

so i completely ignore this instruction
"
- Use the CMOS clear jumper on the motherboard.. set it to clear... turn on the power for a bit, turn off the power again, then replace the jumper to its normal setting, and see if it boots
"

i tried to remove the cpu but it seemed to be tightly fit. i have never cleaned the fan of the cpu,only removed some of the acumulated thickened duton the top every now and then. do you tink i should get one of those cans of compressed air and blow away the dust.

when you say re-seat any cardsyu may have installed (vieo,sound,lan),you mean cards installed recently.
i had installed an edimax wifi carda month ago, do you think this card may be the issue. wouldnt such a card cause issue in the begining.

i just tried to turn on the pc after letting it rest for a number of hours. and it gt to the "boot from cd or boot from hard disk" step, last night it had only managed to get to go through the memory test (RAM)
after the computer shut down again, i tried to start it up again, this time, it ould not go beyond the memory test. does this indicate that somethingis heating up due to the fan not working and hence something turns of the pc?

this testing wold not affect the content present on the hard drivces, correct?

 

[mpilchfamily]

The HDD should be fine but the system cutting out in the middle of a boot up may currupt some system file. If that turns out to be a problem a repair install of windows will correct this.

Its sounding more and more like a heat issue. You mentioned a fan wasn't working. Which fan is it? If its the CPU fan then the system is certainly overheating. So you need to get that working again before you attempt to go any further. But if the system is overheating it will shut itself down to prevent damage to the CPU.

 

[RadiclDreamer]

Originally posted by: myocardia

Originally posted by: phaxmohdem
- Use the CMOS clear jumper on the motherboard.. set it to clear... turn on the power for a bit, turn off the power again, then replace the jumper to its normal setting, and see if it boots

Do NOT do this. You don't supply power to something with it intentionally shorted, which is what moving the CMOS jumper to the Clear position does-- it shorts out the CMOS chip. The rest of your post is very good advice, though.

I've done this literally hundreds of times with no issues

 

[rookie1010]

thanks for the replies,

i tried to clean the cpu fanand heat sink.
switched the pc on, and it went through the POST and then cut out after getting to the "boot fromcd" instruction.

i tried to remove the fan+heat sink from the motherboard after pulling and pusing the levers (on either side)
now i get the same bhaviour, but this time i dont even get anything on the screen, the beep before display of the POST routine has also gone now.
have i damaged the motherboard for good?