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Crackling noise from internal speaker

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February 10, 2010 11:35:32 PM

I have scratched my head for over a week now trying to figure out a strange noise problem. Tonight I was finally able to duplicate the noise several times allowing me to isolate it.

Situation: New power supply (OCZ ModXtream Pro 700W, replaced Antec Smart Power 450Watt) was added to support a new video card that was more power hungry than the 450Watt PSU could handle.

All was well initially. Then about 24 hours after installing it I started getting a strange noise while the computer was in sleep mode (my computer goes to STR (S3) sleep as it's a HTPC that needs to wake up for recordings and maintenance from time to time but doesn't need to suck down power 24/7).

The noise was a crackling noise that sounded similar to an electrical short. The first time I heard it I quickly hit the power button planning to turn off the computer, but it was in sleep mode so that just woke it up - and the sound stopped instantly. I ran the computer for a while and the noise never came back. Since it sounded like a crackling noise I assumed it was the power supply and just did a full power down for the night and turned off the main power rocker switch on the back of the PSU with plans to check it out later - it was past my bed time :) 

I finally got a chance to try to duplicate the problem later, and was unable to get the noise. I tried several times, but was afraid to leave the computer on overnight or when I was out of the house in case it was some sort of electrical problem with the new PSU.

Today after dinner the computer had been left on, and went to sleep. I heard it making the noise from the living room and rushed back. I opened the case, verified again that no fans were running (they weren't) and tried to isolate the noise. It sounded like it was in the front of the computer (near the power button) and then also sounded like it was in the PSU. Then the sound faded away.

I woke the computer up and gave it a minute or two then put it back to sleep. After about 30 seconds or so the sound started softly then grew louder, carried on for 30 seconds or so then faded out and eventually quit. I repeated this cycle several times listening carefully all over the inside of the case and around the front. Finally I remembered that the pc speaker (built into the case) was near the power button, where the noise seemed to be coming most loudly from.

I cycled again and when the noise started and got loud, removed the internal speaker connection from the motherboard. The noise stopped.

Now I know where it's coming from and how to stop it :) 

What I want to know is 1) if anyone else has ever seen this and 2) what the cause could be.

I suspect it's a capacitor in the new power supply bleeding off power after going into low power mode (S3, or STR, suspend to ram). I figure this is the case since I didn't have this issue with the old PSU and other than the video card nothing else has changed. I guess it could be the video card as well. I guess it could be something with the motherboard as well, but again it all started with the new PSU and video card.

If it's the PSU then is it something to worry about? I can RMA it and do an exchange if that's the problem. Same applies to the video card.

Suggestions? Should I swap out the video card and try to duplicate with the old video - it's a PITA to do but I guess could be necessary.

Thanks!
February 11, 2010 1:11:13 PM

Sounds like static electricity building up...
Ground the PSU (3rd wire) and it should stop.
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February 11, 2010 2:37:10 PM

The PSU is properly grounded and is using a properly grounded outlet. Hmm ....
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February 11, 2010 6:41:37 PM

It's definatly the power supply i had an old system that did the same thing and the system ran forever with no problems this was a couple years ago in an old P4 system. I was building a new rig and that had a corsair 600 watt PSU in it and i took it out to transfer to my new rig and put a cheap 300 watt PSU in it cause it was primearly gonna be used as a file and print server on my network, after putting the cheap PS in it it stoped doing that and as for the new rig i put that PS in did not make the noise so your not the only one that has had this problem but i have no clue why it made that noise but it did. If i were you i would RMA the PS and if that dont work disconnect the speaker and forget about cause it shouldnt hurt anything it didnt in my case.
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February 18, 2010 12:01:33 PM

Saaiello,

thanks for the reply. I've just disconnected the internal speaker. The PSU is performing fine so far (outside of this strange noise). It's got a 3 year warranty so if I run into problems it will surely be during that time frame, and if not it will serve as a good excuse to do a full upgrade :) 

I would hate to do an RMA at this point since I have a rebate in process on the unit. I would probably have to go through the manufacturer and their turn around times are slow slow slow from what I've seen on their website forums.

Thanks again,

A
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February 24, 2010 3:28:36 AM

Hah, I have the same thing after my 400W Coolermaster power supply died and got replaced with a 460W one (same brand). It starts crackling like a Geiger-counter after a minute of going to hibernate mode. If I unplug or power-off my LCD screen, the noise stops immediately. There must be something different about the new power supply that causes this..
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