Fan wa wa sound

February 17, 2017 at 16:13:01
Specs: Linux x86_64, i7 6700/12 GB RAM
I have a pretty new Asus desktop tower machine. I decided to break the warranty sticker and open it up and put in a Nvidia Geforce 750 card. PC runs really nice but I have a really light waa waa pulsating sound. If I hold the side of the case, it goes away. If I move the side loose, it goes away temporarily. I think it's just a harmonic imbalance between the cpu fan and the gpu fan. Does anyone know how to dampen the noise effectively?

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#1
February 17, 2017 at 16:22:13
It could be harmonic imbalance but another possibility is that something is touching something else, such as the fan on the casing. It could be amplifying the sound when in contact. If it only came along after installing the card then see if the card can touch the case when assembled. Maybe plastic foam can be stuck somewhere to prevent firm contact.

Keep trying because you seems to be on the right track generally. It can only be sorted by inspection and a bit of trial and error.

Always pop back and let us know the outcome - thanks

message edited by Derek


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#2
February 17, 2017 at 16:28:39
For the fun of it, here's a pic. The inside of the case is pretty clean and clutter free.

https://www.dropbox.com/s/0yhv0btq5...


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#3
February 17, 2017 at 16:30:41
It sounds fine with the side off... but I know it's not good for the airflow.

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#4
February 17, 2017 at 16:33:04
Excuse multiple edits to my #1 - it's settled now.

Having seen your snap the likelihood of something touching the case now looks low - there seems to be plenty of room in there.

Always pop back and let us know the outcome - thanks

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#5
February 17, 2017 at 16:46:56
Ok, I do this all the time. I post something and then figure it out. (It's like in my mind, i'm not 100% committed to fixing it until I post the question. Then I'm all in.) I am not 100% sure it's fixed. But I changed the screws from the factory ones which had a round head philips to ones with the hex head philips. They're both the same threadsize. I'm thinking it might be helping more because the hex head has deeper groves for the philips head so I was able to snug the screw a little more without feeling like I was going to strip the screw head (even though obviously I'm being very cautious of stripping the threads in the case... obviously those threads in sheet metal are not very good and easily stripable.) But some reason, it just feels like I can snug those screws better. Also, I'm wondering if the surface area where it meets the case is a little larger and helping hold the case better.

But I still think I hear the pulsating noise very ever so lightly...

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#6
February 17, 2017 at 17:05:14
OK - keep us posted.

Always pop back and let us know the outcome - thanks


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#7
February 17, 2017 at 17:26:24
I assembled a desktop in an Antec Designer 500 mid-tower case,
which was supposed to be especially quiet, with side panels inside
made of some kind of polymer that were claimed to damp noise.
It had a built-in 120 mm exhaust fan in the back in addition to the
smaller PSU fan, and I added a circular CPU fan that looked a lot
like yours (Thermaltake "MeOrb") that had a low noise rating, a fan
on the Sapphire Radeon graphics board, and two low-noise fans in
the front, in front of the hard drive bays. The fans that could be
adjusted were usually set to the lowest of the three speed settings.

The darn thing was louder when it was closed up than when the
side panel was off. Well, the side panel on the side away from my
sitting position. I could never tell exactly where the sound was
coming from, but it seemed to be coming through the vent holes
in the front cover, as if the airflow through those vents increased
when the side panel was closed. The combination of sound from
the fans plus sound from the refrigerator in the kitchen nearby led
me to use earplugs while at the computer for several years. The
refrigerator where I am now is much newer, but is even louder.

-- Jeff, in Minneapolis


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#8
February 17, 2017 at 18:06:41
The pulsating is slowly getting worse. I'm not sure what to do other than somehow add padding between where the case door and case meet. I'm not sure if transplanting the whole PC into a different case would make a difference.

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#9
February 17, 2017 at 18:28:40
Is it the same with the previous card? If not I suppose it could be a faulty fan on the new one.

Always pop back and let us know the outcome - thanks


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#10
February 17, 2017 at 18:36:35
The "previous card" was onboard which is still there. I don't think the fan is defective. Maybe. The pulsating noise can be so quiet but it's just there.

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#11
February 17, 2017 at 19:09:07
Ok, I just ordered a mechanics stethoscope so I can hopefully pinpoint exactly what in the pc is causing the vibration.

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#12
February 17, 2017 at 19:37:32
You can always just use your finger to stop a fan from spinning. (Don't use a screwdriver as that can break a fan blade.) Then if the sound goes away you know that particular fan is part of the problem.

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#13
February 17, 2017 at 21:20:23
Was the noise there before you removed the side panel? (Break the seal)
Are you sure you slide the side panel back into the grooves designed to close off the side of the box?

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#14
February 17, 2017 at 21:52:59
For a SHORT test unplug the case fan (one at a time if more than one). If the sound does not appear then it is from there. Either replace the fan or try thin rubber like from a bicycle inner tube.
Try reseating the graphics card since if it seats slightly more or less the lock down clip and screw may hold it more firmly. Try a small piece of electrical tape under the tab that is secured to the case as it may isolate or tighten it better.

You have to be a little bit crazy to keep you from going insane.


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#15
February 18, 2017 at 06:15:45
"I just ordered a mechanics stethoscope"

All you need is a short length of tubing or hose or even a straw to help pinpoint the noise.


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#16
February 18, 2017 at 06:52:28
Yep, I've used a piece of wood (dowel) to transfer sound to the ear.

Always pop back and let us know the outcome - thanks


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#17
February 18, 2017 at 15:55:00
If the side panel is screwed on then loosen the screws and push and hold the bent edge toward the center of the case. Tighten the screws while holding in that position.

Make sure the side panel is correctly installed too.


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