Help! Computer won't stay on more than 1 sec!

[Nicholasp27]

I built an Athlon system as follows:

Abit NS7-S2 mobo w/Athlon XP 2600+ (barton)
geforce fx5600
120mb ide hdd
dvd rw
dvd rom
512mb pc2700 ddr
coolermaster fan/heatsink on chip

i built it and it would power up but no signal to monitor...finally i found that i had to move the cmos jumper (the manual had reset vs regular backwards) and it booted on..looked at bios and saw cpu temp was 97 farenheit...set the cpu shutdown to 140 degrees...i inserted my winxp cd and had it format the hdd...came back 5 mins later and the computer was off...

now when i turn it on, it comes on for about 1 sec (fans come on, but no signal in that short of time) and then turns off....i then have to flip the psu switch to off and then back on before i can turn it on again for another second...it won't re-turn on unless i flip that...

what could be causing this?

i'm thinking psu, mobo, cpu...but i'm hoping it's not a defective product...what can i do to check everything and find out what is causing this strange problem? i must figure this out tonite, as i'm taking it with me to my nephew's tomorrow, whom i built it for...


when i turn the psu on, a red led comes on in the front of the mobo...when i turn on the computer, a yellow one comes on next to it to let me know the power is on...then when it dies, i cannot turn back on the computer at all unless i turn off the psu until the red light is off...so it sounds like the mobo is causing the psu to cut off, so doesn't sound like a psu problem?

i unplugged the ide cables and even took out the memory..

ok, i took everything off and took the motherboard out of the case to make sure nothing is shorting it out...i connected only the two power connections to the mobo from the psu and the power sw from the case to activate the power button...still doesn't come on...

could cpu cause that at all, or would it take longer for the mobo to cut off if it was the cpu? if cpu can't cause that, then it's either the psu (unlikely) or the mobo (likely)..


any helps, thoughts, ideas, suggestions?

 

[aceadrian1]

Initially I would check the voltages your PSU was giving. As you haven't listed it with the rest of your components, I'm guessing it's just a generic thing. If your PSU is giving rotten voltages, then it could already have damaged other components. To test the voltages without access to the BIOS and without being able to try another PSU;

Instructions on PSU testing with a multimeter

The first step, wedging a wire in two pins, just tricks the PSU into thinking it's plugged into the motherboard. Be careful...

 

[montag451]

its hard to tell exactly what the problem is without hearing POST beeps/codes, or swapping out hardware.
If it is the CPU, the machine might not switch on at all [the cpu is the first thing to get power after the mobo, and if the cpu can't give out an inbuilt instruction, everything stops dead].
or it is possible that a cpu could give you that prob.

If it is mobo prob, could do the same, as well as a million other things.

One last simple shot:
try clearing cmos - unplug computer, and take out battery, as well as using the jumper - leave out for 20 minutes.

if that doesn't work, try a new battery if you have one lying around.

otherwise, could be PSU/cpu/mobo
sorry = can't be more help - only telling you what you already know

 

[Fern]

Hi Nicholasp27 and Welcome to the Forums!

Just a thought, do you have the fan (from the cpu's heatsink) plugged into the correct mobo header? If the mobo can't sense the HS fan at a fast enough speed it will power down the mobo.

Also visually confirm the HS fan is spinning.

Fern

 

[mechBgon]

And confirm that your heatsink is on like in the third photo on this page. If you had the clip out of the heatsink at all, then also confirm that its pressure point is over the CPU core when the heatsink is on in the correct direction, since it's asymmetrical.