constant high pitched sound (probably not coil whine)

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Urlusup

Commendable
Jan 8, 2017
4
0
1,510
Hello everyone,

so after perusing google results and a ton of threads on this forum, I still have not come across something resembling my particular problem. I'm at my wits end.

I've been using this PC for 6 and a half years now, so there haven't been any hardware changes.
3 days ago I got this constant high pitch on my headphones (not from the case) and after trying it out I could confirm that I get it from every possible audio output. That means I get it
-from the 3.5 mm jack of the motherboard.
-from my USB external sound card
-and even from my monitor via the HDMI cable
(btw the various outputs don't have to be actively used, simply being connected to the PC is enough.)
-If however I plug in my speakers and just use them, rather than headphones, then the sound suddenly disappears! How is this possible? Is it the dedicated power supply of the speakers? Wouldn't it then also "guard" the headphones?

Another "funny" aspect is that the pitch is not influenced by volume or even by any electricity being fed into the system. Thinking it might be residual energy, I've had the PC unplugged for 15 hours before and still the noise was being emitted, from a machine without power!

This more than anything made me throw my hands up in frustration, I cannot fathom how this is possible!

So, I hope someone more experienced might have an idea what's happening, my current theory is Gremlins.

Thanks
 
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aquielisunari

Judicious
Mar 31, 2011
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It may be showing its age. The Gremlin's name is EMI. Emily is an audiophile's worst nightmare and nemesis. Can you change where the sound is coming from? By that I mean removing the external sound card and using the integrated outputs. Are all unnecessary recording devices muted? Right click speaker icon in your task tray and click on recording devices. Mute/disable all of them just to see if there is any change. Either electromagnetic interference or speaker feedback loop.
 
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Urlusup

Commendable
Jan 8, 2017
4
0
1,510
Hi,
thanks for responding.

Yes I tried multiple headphones and no, no other devices are present.

The only gadgets currently plugged in or even in the vicinity of the machine are keyboard and mouse, the router and the speakers. Of those everything has been removed for testing purposes at some point. I literally had the computer sitting there with no cables plugged in whatsoever, yet still emitting the pitch whenever I would connect a headphone to it.
Speakers are fine for some reason.

aquielisunari, you mentioned the dreaded Emily or EMI. Since the problem appears to be located somewhere in the closed system loop of the PC itself, would you know of any components which could cause such an interference due to old age?
Also are 15 hours enough to get rid of any residual power in a computer? Whatever is causing this sound, how does it do it without electricity?
 
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aquielisunari

Judicious
Mar 31, 2011
6,499
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33,015


Idk. That's a tough one.

Do you have an Acer monitor? Is EVERYTHING off and unplugged when you hear that sound? Not only your PC. Speakers, EVERYTHING.
 
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Urlusup

Commendable
Jan 8, 2017
4
0
1,510
No the monitor is an Lg Tv but since I indeed had absolutely nothing connected to the PC except the headphones, I kinda doubt that the monitor is even a variable.

My last idea right now is to open up the case and try to somehow ground the innards. Maybe this could get rid of whatever residual power remains in the system, assuming that is even the cause.
 
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aquielisunari

Judicious
Mar 31, 2011
6,499
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The PSU, the cord, the recpticle and your house takes care of grounding. That is assuming you have 3 prong(GFCI or not) outlets.
 
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Urlusup

Commendable
Jan 8, 2017
4
0
1,510
Alright so I managed to get rid of the noise, at least for the moment.
It would seem that the fault lies with the air conditioning unit. I realized just this morning that its emitting an irritating sound of its own and when powering it down, the high pitch disappears from all electric appliances (TVs, radio etc), except the computer. The PC still chirped on happily , even without a power supply. I remedied this by essentially "sucking it dry" with my headphones. Plugged them in, the pitch was loud but it gradually became quieter until it was gone completely. Headphones need some energy to function after all. I did the same thing with my external sound card, which held some charge of its own, even while disconnected from the PC.

So in the end it probably was the dreaded Emily, I just had to broaden the search.
I don't know enough about electricity to form an opinion whether this retention of interference in powered down equipment is normal or if that means that my PSU is not performing its grounding duty. I'd appreciate a heads up if that's a precursor to hardware failure or some other catastrophe.
Thanks.

Now to see what the blasted ACs problem is......



 
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aquielisunari

Judicious
Mar 31, 2011
6,499
14
33,015


Thanks for that. It's a beautiful thing to see that sound went away. How much amps are you pulling on that circuit. Not only on that one plug but that circuit? I've seen(heard) surge protectors scream in pain when they are overloaded but like you said this does seem like an EMI case. It's an odd solution but https://www.amazon.com/Tapes-Master-10ft-Copper-Foil/dp/B00Z8MCK6M MIGHT possibly work. Sure it's a musician's best friend but if you tape the side that is facing your setup it MIGHT help. Then again it may be that you are asking for too much power.

Please keep us updated.
 
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