LOUD buzzing Desktop

[Outdoor Writer]

I'm going a bit nutso today. Yesterday afternoon, my 2-yr. old HP desktop started this loud buzzing noise (not a humming sound). It sounds like an old alarm clock. My wife could hear it in her TV room, and my office door is a long way from there.  Yet it's running just fine otherwise. 

So I tried to find the cause. First, I shut down the computer; the buzz continued. Next, I pulled the power cord; the buzz continued. Then I pulled off the side cover and using a pencil eraser, stopped each of the fans while the machine was running; the buzz continued. Now it was time to isolate some of the hardware by disconnecting wires. I started by turning off the desktop and unplugging the main power supply to the mother board; the buzz continued. I followed by disconnecting the HD, CD drive and card reader; the buzz continued. 

After a few hours of messing with it, I turned it off late yesterday afternoon and unplugged everything connected to the case; the buzz continued. When I came out to my office this morning, I could hear the buzz was still going as soon as I hit the kitchen for my coffee. And my hearing is so bad that I have two hearing aids, which I didn't even have on. 

This morning I decided to try a couple other things. Since the buzz continues even when there's no AC power, I thought the battery might be providing the power to keep it buzzing. I pulled the battery; the buzz continued. Then I removed the four screws holding the power supply in place and pulled it out far enough to figure out it wasn't doing the buzzing.

Now I'm completely stumped, especially about how it goes on without any AC or DC power. The only thing I can't check easily is the CPU and the rest of the other motherboard parts. 

Any computer experts have a suggestion other than take it to a computer tech?

[Jazz]

Computer parts don't make sounds without electricity.. That's REALLY weird.

Sure something isn't stuck? Like a bug or something?

[cjl2010]

This should stop the buzzing...

[Outdoor Writer]

2 minutes ago, Jazz said:

Computer parts don't make sounds without electricity.. That's REALLY weird.

Sure something isn't stuck? Like a bug or something?

Well this one does, and loud noises at that. 

[Outdoor Writer]

1 minute ago, cjl2010 said:

This should stop the buzzing...

I might eventually resort to that. It's so bad, I have to take breaks to clear my head. 

[forepaw]

11 minutes ago, Outdoor Writer said:

I'm going a bit nutso today. Yesterday afternoon, my 2-yr. old HP desktop started this loud buzzing noise (not a humming sound). It sounds like an old alarm clock. My wife could hear it in her TV room, and my office door is a long way from there.  Yet it's running just fine otherwise. 

So I tried to find the cause. First, I shut down the computer; the buzz continued. Next, I pulled the power cord; the buzz continued. Then I pulled off the side cover and using a pencil eraser, stopped each of the fans while the machine was running; the buzz continued. Now it was time to isolate some of the hardware by disconnecting wires. I started by turning off the desktop and unplugging the main power supply to the mother board; the buzz continued. I followed by disconnecting the HD, CD drive and card reader; the buzz continued. 

After a few hours of messing with it, I turned it off late yesterday afternoon and unplugged everything connected to the case; the buzz continued. When I came out to my office this morning, I could hear the buzz was still going as soon as I hit the kitchen for my coffee. And my hearing is so bad that I have two hearing aids, which I didn't even have on. 

This morning I decided to try a couple other things. Since the buzz continues even when there's no AC power, I thought the battery might be providing the power to keep it buzzing. I pulled the battery; the buzz continued. Then I removed the four screws holding the power supply in place and pulled it out far enough to figure out it wasn't doing the buzzing.

Now I'm completely stumped, especially about how it goes on without any AC or DC power. The only thing I can't check easily is the CPU and the rest of the other motherboard parts. 

Any computer experts have a suggestion other than take it to a computer tech?

Could you have a capacitor that is retaining a charge?  If so, and if a relay or other component has failed or become stuck, that could be a possible source.  A capacitor has to be manually discharged using a screwdriver or other conductor across both poles.  It sounds like some component is trying to start or run.

forepaw

[PRDATR]

With it unplugged hold the power down for 15 seconds.

[Outdoor Writer]

1 hour ago, forepaw said:

Could you have a capacitor that is retaining a charge?  If so, and if a relay or other component has failed or become stuck, that could be a possible source.  A capacitor has to be manually discharged using a screwdriver or other conductor across both poles.  It sounds like some component is trying to start or run.

forepaw

We're getting a bit above my pay grade now.  😉 Yet I would be able to do that if I could get to the motherboard components easily. I can't without removing it, which means dismantling a few other hardware pieces to get it clear out of the case.  But that begs the question; if what you said above is happening, wouldn't that have some impact on how it's running? Like right now, there's nothing wrong. I've even rebooted several times since the noise began. 

[Outdoor Writer]

2 minutes ago, PRDATR said:

With it unplugged hold the power down for 15 seconds.

I'll  give it a try in a little bit. Thanks for that suggestion. 

[Outdoor Writer]

20 minutes ago, PRDATR said:

With it unplugged hold the power down for 15 seconds.

Just tried it. Held the power button down for varying lengths of time. No change. The buzz continues. 🤬

[Snapshot]

Computers have an internal standby power supply. It is used to keep the internal clock running. If there is a short, or possible dust buildup, it could cause internal caps to buzz on the motherboard, or transformer.

You could pull out the PSU, and disconnect the clip in wire harnesses that power the various hardware, one by one, and see if you can isolate the problem.

Does it have an internal speaker?

[Outdoor Writer]

2 minutes ago, Snapshot said:

Computers have an internal standby power supply. It is used to keep the internal clock running. If there is a short, or possible dust buildup, it could cause internal caps to buzz on the motherboard, or transformer.

You could pull out the PSU, and disconnect the clip in wire harnesses that power the various hardware, one by one, and see if you can isolate the problem.

Does it have an internal speaker?

No internal speaker, and I pulled the battery out this morning to no avail. I also did the disconnect each HW component thing yesterday and also disconnected everything at once, including the main plug from the PSU to the motherboard. I've been messing with and doing R&R on these things since 1985, but this one has me baffled. I might just wear my shooting muffs and say screw it. 🤣

[Tropicalmulch]

Hose it down with big spray. Sounds like you havea cicada stuck in there!

[Snapshot]

Is there any noise coming from the PSU itself, when everything else is disconnected?

[Outdoor Writer]

3 minutes ago, Snapshot said:

Is there any noise coming from the PSU itself, when everything else is disconnected?

No. I actually pulled it out of the case to get it a bit away. Put my ear right against; no buzz.  I'm going to pull the CPU cooling fan in a bit to see if there excessive dust built up under it. Hard to see down in there with the fan cage in the way.

 

6 minutes ago, Tropicalmulch said:

Hose it down with big spray. Sounds like you havea cicada stuck in there!

  You know, that's close to the sound it's making.