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computer won't start, probably bad PSU or mobo

by SilentT / November 20, 2004 2:59 AM PST

Hi, I'm trying to help my roommate with his computer, but I need some help
figuring out what's wrong with it. I don't know all the specs, but it's got a
P4 and has been working acceptably up until now. This morning he tried to turn
it on and it wouldn't boot. I've opened it up, and a green led on the mobo is lit
whenever the computer is plugged in, which makes me wonder if the PSU is ok.
When I try to turn on the computer the CPU's heatsink fan spins for a second,
and then stops, which also seems to indicate that it's getting power. The PSU
fan does the same thing: spins for a second and then stops. If I hit the power
button after that nothing happens. If I unplug the computer for a few
seconds the led will go out, and when I plug it back in and hit the power
button the fans will again spin for a second and then stop. The fact that at
least some juice seems to be flowing makes me wonder if the mobo, not the PSU,
is the problem. Any advice would be greatly appreciated.


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Re: computer won't start, probably bad PSU or mobo
by SilentT / November 20, 2004 3:12 AM PST

OK, this is really weird: it occurred to me that the power cord might be faulty, so I replaced it with one of my power cords, and it booted up fine. I unplugged it, put the old cord back, and now it's working fine again. What in the world does this mean?

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Re: computer won't start, probably bad PSU or mobo
by SilentT / November 21, 2004 5:43 AM PST

It happened again; the fans will spin when the power button is pressed, but it won't start. Is there any way to figure out what the problem is without buying a new PSU to try out? I could really use some help with this.

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Re: computer won't start, probably bad PSU or mobo
by Michael Geist / November 21, 2004 6:48 AM PST

PSUs fail in all different ways. Some go Snap, Crackle and Pop, some die a slow stuttering death. The first step is to swap it out and see if the problem disappears.

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having same problem, tried a different PSU already
by mooncrow / January 6, 2005 1:50 AM PST

I'm having a similar problem - system starts to power up, and then shuts itself off after 2 or 3 seconds. I have tried using a PSU from another case and still no joy. Could this be a bad connection or a bad cooling fan for the CPU or something else that I can check?


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