PC turns off unexpectedly

[arthurceej]

I bought a PC two and a half years ago and it had been working
flawlessly. Just last weekend, it started turning off unexpectedly.
When this happens, the monitor light will change from green to orange.
All the fans and HDs stop spinning. Everything looks as if the machine
has no power except that the main green LED still stays on and won't
turn off no matter how long I keep holding down the power button. If I
release the button and press it again, the machine will turn back on.
I can then use it as usual and it can be left on for 10 minutes up to a
few days before it turns itself off again, even when it's idle (no
application running at all).

Every time when this is about to happen, probably 1-2 minutes before it
turns off, I can smell something burning (like plastic burning, I
guess) but it's not a strong smell. Is this problem caused by the PSU,
the mainboard or something else?

The PC is an HP Pavilion 751x. The mainboard seems to be an MSI
MS-6367. The OS is Windows XP/SP2.
Can anyone help, please?

Thanks,
Art

 

[john_20_28_2000]

Make a backup. I suggest a new power supply. You could open the case
and smell or see where the smell is coming from, maybe.

 

[w_tom]

Make those backups. But do not start wildly replace
things. Better is to first collect facts such as information
from the system history (event) logs, Device manager, AND if
it is the power supply - a 3.5 digit multimeter. If power
supply is the problem, those voltage readings would identify
the problem now - before complete failure happens. Some
previous posts demonstrate how to determine power supply
integrity in less time than it took to post:
"Computer doesnt start at all" in alt.comp.hardware on 10
Jan 2004 at
http://tinyurl.com/2t69q and
"I think my power supply is dead" in alt.comp.hardware on 5
Feb 2004 at
http://www.tinyurl.com/2musa

 

[DaveW]

Most likely the power supply unit is failing.

 

[arthurceej]

I bought a PC two and a half years ago and it had been working
flawlessly. Just last weekend, it started turning off unexpectedly.
When this happens, the monitor light will change from green to orange.
All the fans and HDs stop spinning. Everything looks as if the machine
has no power except that the main green LED still stays on and won't
turn off no matter how long I keep holding down the power button. If I
release the button and press it again, the machine will turn back on.
I can then use it as usual and it can be left on for 10 minutes up to a
few days before it turns itself off again, even when it's idle (no
application running at all).

Every time when this is about to happen, probably 1-2 minutes before it
turns off, I can smell something burning (like plastic burning, I
guess) but it's not a strong smell. Is this problem caused by the PSU,
the mainboard or something else?

The PC is an HP Pavilion 751x. The mainboard seems to be an MSI
MS-6367. The OS is Windows XP/SP2.
Can anyone help, please?

Thanks,
Art

The power supply is the problem. I didn't notice that its fan had
failed. I will go get a new one this weekend and hopefully everything
will be working fine.

Thank you all for the help and suggestions.