Strange Hum/Vibration Noise

[Salv]

Hello.

After cleaning my PC last week, I've noticed a sound that I don't believe I've ever heard it make before. It's low/medium pitched and seems to be mechanical, not electrical.

Although I'm having trouble locating the exact source, it is most apparent when placing my ear around the area where the side meets the front panel (where I sit naturally) or in the space towards the back of the case, between the PSU, CPU, rear fan and GPU. As far as I can tell, it's usually inaudible until the system is under load. If, for example, I launch a game, then the sound will slowly ramp up and continue until closed, at which point it will fade after a short period.

The best description I can give it is a hum or vibration. Unlike a fan, the noise fluctuates but it is still constant and the volume does match an increase/decrease in fan speed. This makes me think it may be something causing the fan to spin improperly, like a loose bearing or alternatively, perhaps it's just weird airflow?

If it is a fan problem, I'm confident it's not the graphics card as limiting the speed to sub-idle levels makes no difference. Aside from the PSU which is difficult to observe, none of the fans are stopping or catching on anything either. I've checked for loose cables and screws. So far, I've not seen any abnormal temperatures.

Would anyone be able to advise me on what I could or should be doing next to try and resolve this? The sound itself isn't particularly 'destructive' yet I do worry that it might be indicative a fault that is developing or has already developed.

For reference, I have the following:

i5 3470
HD 6870
Corsair TX650

Thanks.

 

[denis280]

could be a case vibration.and if you think its the gpu or cpu.what i do is gently put a finger in the midle of the fan.make sure to be grounded to the case.

 

[Bubbaleone]

Any rotating device creates noticable vibrations at certain rpms. These are known as harmonic vibration. Having all the attachement screws in your computer case securely tightened will ensure that fans don't cause any of the case components to produce an audible hum.

EDIT: Another overlooked aspect of humming sounds coming from the computer case is when a fans bearings have become degraded. When that occurs, the shaft rotating in the bearing can no longer revolve in a concentric axis, thus producing abnormal vibrations.

 

[Salv]

could be a case vibration.and if you think its the gpu or cpu.what i do is gently put a finger in the midle of the fan.make sure to be grounded to the case.

This isn't a new PC though. It's around 10 months old now, so unless the case itself has contorted, wouldn't it have always made the same sound? It's loud enough that I almost certainly would've noticed it before.

Any rotating device creates noticable vibrations at certain rpms. These are known as harmonic vibration. Having all the attachement screws in your computer case securely tightened will ensure that fans don't cause any of the case components to produce an audible hum.

EDIT: Another overlooked aspect of humming sounds coming from the computer case is when a fans bearings have become degraded. When that occurs, the shaft rotating in the bearing can no longer revolve in a concentric axis, thus producing abnormal vibrations.

Are degraded bearings a problem beyond the extra noise they create? I can tolerate it if it's a superficial issue.

 

[mindless1]

Yes degraded bearings are a problem in that they cause extra stress and wear much faster. It could still run for years, or fail to spin at all the next time the system is powered on and off. It's highly variable.

Ultimately you have to dig deeper. Keep the side panel off and see if there is vibration. If not, it would seem the side panel causes it. It could easily start, or stop, vibrating from minor changes if the panel is removed, or the whole system is picked up but fortunately this kind of vibration is easily solved by flexing the vibrating part or adding a little masking tape or something else as a shim to cushion the area.

No point in much speculation besides it being a fan or hard drive, you just have to catch it when it happens or spend a lot of time running the system with individual parts unplugged and assume that part was the cause.

 

[Salv]

Yes degraded bearings are a problem in that they cause extra stress and wear much faster. It could still run for years, or fail to spin at all the next time the system is powered on and off. It's highly variable.

Ultimately you have to dig deeper. Keep the side panel off and see if there is vibration. If not, it would seem the side panel causes it. It could easily start, or stop, vibrating from minor changes if the panel is removed, or the whole system is picked up but fortunately this kind of vibration is easily solved by flexing the vibrating part or adding a little masking tape or something else as a shim to cushion the area.

No point in much speculation besides it being a fan or hard drive, you just have to catch it when it happens or spend a lot of time running the system with individual parts unplugged and assume that part was the cause.

The side and front panels don't seem to affect it, though I suppose it might be worth applying pressure to other areas of the case. I'm also going to redo my cable management to ensure that's not causing any vibration. I'm not willing to risk running without fans for any amount of time but if I can manually limit the speed as I did with CCC for the graphics card, I will. Is there any software that would allow me to do this for the CPU/PSU/rear fan?

 

[mindless1]

If it's a fan vibrating that bad then either the bearing is shot, or the fan is badly imbalanced and/or loosely mounted and rattling a lose portion of the case.

It's not a big deal to unplug a fan for a few seconds. Leave the case cover off, then when you hear the noise reach in there and pull the plug. Plug it back in if the noise doesn't stop, cutting off as few fingers in the process as possible.

 

[Steltek]

You said you cleaned your machine. Could you by chance have missed a single fan blade that is coated with dust or dirt which could be causing vibration? Also, definitely check the mountings for the case fans to ensure you don't have a loose screw that is allowing the fans to vibrate.

One thing you can try to do is, one at a time, unplug a single case fan and run the system without that fan to see if the problem goes away (if you worry about heat, leave the side off the case). Over the course of a few days, you should be able to discover which fan is causing the problem so as to replace it.

 

[atpokey]

I had an older gpu fan begin to make just such a sound, after the oil dried. Definitely sounds like some sort of fan issue, as above I'd go through component by component if its too hard to locate by sound.

 

[bononos]

Hello.

After cleaning my PC last week, I've noticed a sound that I don't believe I've ever heard it make before. It's low/medium pitched and seems to be mechanical, not electrical.
.....

You probably bumped something like a fan which need the screws retightened since it just happened after you fiddled with your case.
Or maybe the case is vibrating (from the fans) and making the sound and just need some readjustment.

If its a case fan that is going bad, you could oil it if it has a rubber plug to facilitate oiling. But it really should be done before it went bad, so you might just replace it and save yourself the hassle.

 

[mindless1]

When all the more common things have been ruled out, you're left with only one possibility.
https://www.google.com/search?q=rattlesnakes+in+my+computer

 

[Salv]

Okay, so I went over the case again. Nothing is noticeably loose after checking all screws with a screwdriver. I removed any remaining dust stuck on fan cylinders and blades with compressed air and cotton buds. I tried to limit contact between unused PSU cables and areas of the case to prevent vibration. Side panels definitely make minimal difference - the noise might resonate more with them attached or the fans disguise the noise better when they're not. Pressuring different areas of the case has no effect. Nor did unplugging the chassis fan. The CPU got too hot too quickly for me to feel I could safely test it.

Other than that, I'm basically out of ideas. It might not even be a fan, so I'm really lost as to what I can even try next..

 

[mindless1]

I must be missing something. You're looking and there's no rattle (= fixed?) or you're looking, you hear a rattle, but you can't pinpoint the direction and distance?

The CPU won't overheat by just stopping the fan for a few seconds. You don't even have to unplug it, can just stick a plastic drinking straw in near the hub to slow it to a stop. Same for the PSU fan and video card if present.

 

[Salv]

The latter, it's still there. The only thing I'm sure of now is that it's not the case fan or dust.

I'm wary of causing other problems by manually inhibiting the fans but I guess I have no choice other than to do so since I'm trying to troubleshoot an issue with no clear problem or source.

 

[mindless1]

It'll be ok, just stick a thin walled plastic straw (like you'd find at McDonalds) in and gently slow the fan to a stop, opposed to thrusting the straw in quickly.

It has to be something mechanical, so unless your optical drive is spinning that leaves only a few things like one of the fans or a hard drive. I mean as the cause of the vibration, then the part it is mounted to or banging against can be isolated or it might just be vibrating itself.

 

[Ketchup]

As others have said, the best thing to do is to manually test every fan in the case. I just do a light finger touch to get each fan to stop, listen, and then more onto the next one, if necessary. Don't forget about the GPU fan. No part of your computer should overheat if you have the fan stopped for a few seconds. If you can't find it this way, you can try the straw method on the power supply.

 

[Salv]

Just thought I'd say thanks for all the responses in this thread, I really appreciate it. I stopped the fans and it was immediately clear that the one on the CPU heatsink was at fault. I received a replacement yesterday and although the fan itself is louder, the weird ambient humming is now gone.

 

[mindless1]

It might've just needed lubed... a drop or two of oil, although the mobo might have fan adjustments to slow the new fan down to where it's no louder than the old one was, or there are fan controlers, or add a series resistor, etc to reduce RPM.