Funny sound from mobo

  • Thread starter Thread starter Atul
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Atul

Hi. Ive an Asus A7V 266 motherboard approx 2 years old. Recently Ive
been running it with case open and noticed that whenever the power is
turned off , the green LED on the board goes off just a few seconds
later (stays on a few seconds, without power from mains/UPS). Also
there is a sound, a very very low sound like a ... well ... whistle
which slowly dies out (its tough to put in words, hope you're getting
the idea).
Thought it might be related to some capacitor charges etc. so I left
the power on (system off) overnight but it did not help. Is the board
dying :( ????
 
Atul said:
Hi. Ive an Asus A7V 266 motherboard approx 2 years old. Recently Ive
been running it with case open and noticed that whenever the power is
turned off , the green LED on the board goes off just a few seconds
later (stays on a few seconds, without power from mains/UPS). Also
there is a sound, a very very low sound like a ... well ... whistle
which slowly dies out (its tough to put in words, hope you're getting
the idea).
Thought it might be related to some capacitor charges etc. so I left
the power on (system off) overnight but it did not help. Is the board
dying :( ????
Click to expand...

The board is probably just fine...
I'm sure it's just a capacitor discharging.
 
Have you checked the motherboard for blown capacitors ? ( bulging, domed topped or fliud
marks around the bottom seal ) It sounds like it could be gas leaking out of one. It may
be one of the coils on the motherboard whistling as the frequency of the switch driving it
drops at power off or the noise may not be coming from the motherboard, it could be the
PSU or its AXT connector for the motherboard.
Another possibiliy is the system speaker, a fault on the motherboard could cause it to
whine for some obscure reason.
--
 
Hi. Ive an Asus A7V 266 motherboard approx 2 years old. Recently Ive
been running it with case open and noticed that whenever the power is
turned off , the green LED on the board goes off just a few seconds
later (stays on a few seconds, without power from mains/UPS). Also
there is a sound, a very very low sound like a ... well ... whistle
which slowly dies out (its tough to put in words, hope you're getting
the idea).
Click to expand...

I've got an Asus P4G8X that does a similar thing. A few seconds after the
power goes off, it goes "eep".

I don't think it's anything to worry about.
 
Thanks for the responses. There are no blown capacitors on the board.
Maybe the sound is normal after all since im not the only one hearing
it.
 
On the motherboard are a collection of torroids ( those small donut shaped
objects with wire wrapped around them). What has happened is that over
time the small amount of glue used to bond the wire to the torroid is
starting to break down. When you disengage the switching power supply the
torroid starts to vibrate over a range of frequencies until the on board
caps are discharged. THIS IS NOTHING TO BE CONCERENED ABOUT. DON'T ATTEMPT
TO FIX WHAT ISN'T BROKEN. I dare say God has blessed you with extremely
good hearing. By the way, the purpose of the glue is to maintain the shape
of wire till the coil is mounted on it's componet board.
 
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