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On my new computer, my fan(s) is/are plain LOUD! Using SpeedFan, I find that my temps are all under 32 degrees C under my normal use (IDK how accurate that is but the CPU itself says 27 C).

The fan doesn't sound unbalanced and it isn't making sounds in rhythm (Not the usual rrrrrrrRRRRRR... rrrrrrrRRRRRR... rrrrrrrRRRRRR... rrrrrrrRRRRRR), just a constant fan. I am thinking about oiling the fans, but I can't decide if it is the PSU fan or a case fan or the CPU fan. If it's the CPU fan I will most likely just replace that with a quiet fan. How can I tell which fan is making the noise (if not multiple)?

One thing that I am thinking may be the problem is my CPU fan isn't PWM so would swapping that out help? There is no "linear voltage" or etc thing in BIOS so I think it may be running at full speed. Also, I could have too much airflow because it is also making a whistling noise that you can hear close to it that sounds like when I accedentially put part of the side cover over my floor vent to get it out of the way.

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why not oil them all –  zinking Jan 13 at 6:44
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did you put your ear near the various fans to see where the noise is louder? –  ratchet freak Jan 13 at 11:12
    
How new? If under warranty, see if they'll swap for you. –  Carl Witthoft Jan 13 at 13:10
    
@CarlWitthoft It's a home build. –  Annonomus Penguin Jan 13 at 23:34
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And this laptop (Vaio) had a problem (loud rattle from the fan) that was apparently due to a wire banging against a thin metal fan shroud. Sony fixed it under warranty, but others reported fixing theirs by simply moving the wire. So look for banging things. –  Daniel R Hicks Jan 14 at 12:04

10 Answers 10

up vote 54 down vote accepted

Use a small piece of plastic (like a pen cap) to stop the fan from spinning. That is the easiest way to isolate the cause. It's okay to stop it for a few seconds while on.

Most fan noise is due to failure of the bearings. Sometimes lifting the sticker on the hub and oiling with 3 in 1 lube will help with the noise.

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Or you can just figure out what the problem is before blindly replacing parts. –  Hefewe1zen Jan 12 at 18:32
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PSU fans can be replaced. Not difficult. But if you're asking this question, you may want to get someone with more experience to help you with that task. –  keshlam Jan 12 at 18:58
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We used to do this on one of our older computers and it worked fine, but word of warning - while a plastic pen cap is probably okay, DO NOT use anything conductive like a paper clip, especially on the power supply fan. A colleague of mine knows that from experience after getting a very nasty shock and tripping all the circuit breakers. He's lucky he wasn't killed - there's supposedly enough charge in a computer power supply to be lethal. –  Darrel Hoffman Jan 12 at 19:02
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I appreciate all the upvotes. People are going to hate on this method but I've been a tech for years and this is how i do it. You're not going to chop of your fingertips. Your CPU isn't going to explode when you pause the fan for one or two seconds. If you aren't comfortable doing this, then don't. Common sense should prevail. (What you shouldn't do is open your power supply and replace parts. Capacitors can dispense enough current to really hurt you. ) –  Hefewe1zen Jan 13 at 1:40
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@Chris H: This is true, but my point is that untrained people shouldn't try to repair (or modify etc.) a power supply in general. This applies to all devices that are non SELV (safety extra-low voltage). –  klingt.net Jan 13 at 10:20

If you can't disconnect or otherwise stop each fan (some may be hard to reach), you can use an old mechanic's trick. Place the tip of a long screwdriver against the body of fan and then press the side of your head (a spot near your ear) against the end of screwdriver's handle. The sound travels through the tool to your ear.

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Instead of a screwdriver, use a wooden ruler (or paint stirring stick etc.). If the screwdriver slips, you'll risk jamming its metal, conductive head into a sensitive electronic component and causing a short. –  Hobbes Jan 13 at 11:33

I'll just put this here as an alternate solution:

Un-plug each fan, one-by-one from the motherboard (or from the PSU, depending on the fan), and when you stop hearing the noise, plug them back in one-by-one until you hear it again (to verify that the one you thought was making the noise actually was). I'd do the CPU fan last; everything else will be fine with ambient cooling for an extended period of time, CPU's most likely to have issues.

Granted if you have a GPU with fans on it you'll probably need to use @Hefewe1zen's method for those ones.

I just don't like telling people to put hard objects and/or fingers near fast-moving objects. Too high of a chance of someone hurting themselves (esp. if they're un-coordinated)

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I'm not coordinated so good advice!!! –  Annonomus Penguin Jan 12 at 22:39
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Actually, if you make the CPU fan the last, then you don't need to disconnect it, as by then you would have ruled out all hypothesis. –  Doktoro Reichard Jan 13 at 1:19
    
Unfortunately, it's impossible to rule out the PSU fan using this technique, as it doesn't connect anywhere externally to the sealed-unit PSU (and you shouldn't go around opening that up unless you really know what you're doing), so you will have to disconnect the CPU fan. FWIW, I suspect the PSU fan is the most likely; I've always found them to be the noisiest in most of my machines. –  Jules Jan 13 at 1:44
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@DoktoroReichard, that is very sound reasoning, but only if you can exclude the possibility that the noises are in your head. –  joeytwiddle Jan 13 at 18:34
    
@joeytwiddle To exclude that possibility, just move away from the computer. Or turn it off. Or ask someone else to do if for you. –  Doktoro Reichard Jan 13 at 19:55

Another method would be to obtain a mechanic's stethoscope, like this one.

Mechanic's stethoscope

Just point the probe at each fan and you'll quickly discover which one is making all the racket.

Or for a cheaper method, use a paper towel tube or similar to focus your hearing, though this doesn't work as well and might be problematic in a tight case.

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or a bendy straw –  ratchet freak Jan 13 at 14:43
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@ratchetfreak - I personally wouldn't be comfortable with that narrow of an object in/near my ear. –  Compro01 Jan 13 at 20:31
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A piece of garden hose worked to narrow down a noisy tappet on an old internal combusion engine. It may work for fans too. Or you could put a small funnel in the ear-hole end of your smaller tube. Small tube is more manouverable and possibly has better transmission with higher frequencies. –  Mark Fitzgerald Jan 14 at 10:40

You could try pwmconfig from a live CD. It basically stops each fan for 5 seconds. See stopping which one is the quietest. It might not be able to stop all fans. Still a software based solution as no one has posted one yet.

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That seems much easier than sticking a pen in a fast-moving object! A nice idea, although I would be reluctant to do this with my CPU fan but then I could narrow it down if it is a case or CPU/PSU. –  Annonomus Penguin Jan 14 at 21:56

You should strive to always have a PWM fan on the CPU block, if the temperature is low, then the fan will run very slow (silent).

On your intake and outtake fans you should at least have a manual adjustment or PWM fans you can control with your motherboard if it supports PWM on multiple fan headers.

If a fan is doing ticking noises or sounds bad, oil may help, but it is a temporary solution which will not work for long. Replace the fans with good PWM fans.

If you are very annoyed with fan noise look into good quality fans that are designed for their purpose.

Noctua imho creates the best low noise fans on the market, although they are ugly as hell. They have different fan models based on what they have to do.

They also include low noise adapters (lower voltage to fan) in all fan boxes in case you do not have any adjustment capability available yourself via motherboard or fan voltage adjuster.

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Don't stop a fan while it's running, you could damage the blades if you're not careful. Stop it while the computer's off and do them one by one, otherwise you'll probably have to replace multiple fans. Look for dust in the PSU fan as it's probably the most enclosed and look for loose wires that might be catching on exposed blades.

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Don't stop it with a knife or a screwdriver - use (as in the earlier answers) a pen cap or the eraser end of a pencil if it will fit. Good point about snagging wires in the general case. –  Chris H Jan 13 at 10:00

Get a cheap medical stethoscope. Seriously.

stethoscoping a desktop computer

I used to be an EMT so I had several lying around. Found they are excellent at isolating noises in anything. When I first starting doing this with my "antique" computers, it was to figure out which hard drive was failing. That's when I discovered that none of these old drives (pre-2000) has failing bearings as I thought. In every case, the noise was from a fan. Most often, the power supply (PSU) fan.

I stop the noise by removing the fan and poking a small hole in the foil cover over the central hub where I put a drop of 3-n-1 oil, then reseal with Scotch tape. Whatever tape used, it should be impervious to oil, have good adhesion and be as light as possible to avoid throwing off the balance. I'm sure there are better oils, but 3-n-1 has worked for me up to a couple of years. I've had one fan I've redone the process a second time and it's still running. Otherwise, just replace it. Fans are pretty cheap, and you can get an even quieter one.

This link to a Google search shows several stethoscopes under $10... https://www.google.com/search?num=30&newwindow=1&biw=1251&bih=590&tbm=shop&q=stethoscopes&sa=X&ei=jqfXUsrtCZLksATr64CwCg&ved=0CC4Quis&tbs=vw%3Al%2Cprice%3A1%2Cppr_min%3A0%2Cppr_max%3A10

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I have two fans on my computer, one for the CPU and one for the PSU. For me, the PSU fan is the nosiest one, and it does the kind of thing that you described.

The first thing you should do is: stop using the computer. Seriously. You could explode your PSU (if it is the PSU fan) or fry your processor, though the BIOS/UEFI and even the processor itself can shut down.

The second thing you should do is: if it is noise, it comes from somewhere. Simply put your ear next to the fan (not on it, you do not want to shock or cut your ear) and listen. You may put a pen cap or your finger in the center of your CPU fan and see if the noise stops.

For the fix: if the problem was in the CPU or system fan, you can solve it with a drop of machine oil on the axis, with is hidden by a piece os paper on the bottom of the fan. If the problem is with the PSU fan, you will have to tear the PSU apart, then you will do the same thing you would do for the CPU or system fan.

And make sure you can do these things :) I wrote what works for me, it might not work for you.

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No. PSUs do not explode. At the very most (and this is for ancient decayed decrepit PSUs), a PSU might squirt electrolytic juice onto the inside of its metal covering, and its fuses might blow out, and the magic smoke might start escaping. (If you are also, for instance, heating it with a blowtorch at the time, this is then actually within the realm of plausibility at that point.) But unless you are talking about a charger for a rechargeable battery, PSUs do not explode. You have probably never handled an explodable PSU, and probably never will. –  AJMansfield Jan 13 at 19:04
    
Stop using the computer? This has been that way for a bit and it doesn't sound unnatural it just sounds loud. Plus, I've left it on for hours at a time and it's fast. –  Annonomus Penguin Jan 13 at 23:40
    
@AJMansfield I've had a Antec 1000 let its smoke out. There was no warning and little load at the time. I personally didn't see it but it was described as a pervading electrical burning smell well before the smoke started. Fortunately no flames before it was disconnected. –  Mark Fitzgerald Jan 14 at 10:47
    
While I have not had a PSU explode, I have had a very large capacitor inside the PSU explode when I was attempting to solder a new fuse into the PSU, apparently I had not discharged the whole circuit, and it is pretty sore (and damaging to furniture too!) –  GMasucci Jan 14 at 14:18
    
@GMasucci "attempting to solder a new fuse". Almost exactly what I said, "heating it with a blowtorch". –  AJMansfield Jan 15 at 13:36

My son's desktop came back from getting fixed by the manufacturer with an annoying fan noise. Since we didn't want to send it back I just started trouble shooting and found there was a piece of a connecting wire too close to the fan blade. I tucked it in and problem solved.

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