Fan Noise?

Ever since I purchased my new box a couple of years ago I've been concerned about the level of noise coming from the computer.
 
It's not enough to trouble a non-audio guy, but it's enough to trouble me!
 
I sent the pc back to Carillon who did the original build and they encased my HDD's in acoustic sleeves, saying this fixed the problem.
 
Well, when I got it back, to my ears there was no improvement.
 
Later last year, I sent it back again and they replaced my original system drive with a 1Tb SSD, but again, the noise levels didn't go down at all. All this leads me to think it's either the CPU fan or PSU fan.
 
Last weekend, I replaced the graphics card and took the opportunity to run it for several hours whilst it was out of the rack and with the covers off.
At first I thought it wasn't working because there was no appreciable noise whatsoever coming from it.
But, as soon as I put the cover back on, I could hear it again.
 
The noise doesn't start when booting up from cold, but gets louder over the course of an hour or so.
 
The cover itself is a fairly massive structure being made from 2mm steel - quite unlike what you'd get from an off the shelf computer, so I think this rules out vibration.
 
So, dear people, any ideas?

Hopefully Bob!

I would look at replacing the fan with fans advertised as "quiet" or " low noise". Over time blades might get slightly warped and start to vibrate which causes noise. Bearings can wear. Dust can be an issue too, but I can't imagine that Carillon wouldn't have cleaned the blades (maybe not).Manufacturers have several ways to get a lower noise with a fan. One way is to use a larger fan running at a lower rpm..this is highly effective. Another way is through bios. If you have a bios that supports fan speed you can have the fan ramp up or down according to cpu temp. Yet another way manufacturers get a lower speed is they add more blades which can move more air at less speed and in this way lower the noise.

Damped or heavy cases don't prevent fan and drive noise getting out because the case has holes in it, though they will prevent case vibrations.

I've been building very quiet PCs since the mid 1990s. The ine in my sig has two fans, never overheats and my decibel meter often can't tell it from room background noise at one metre.

I suggest you look at Noctua's website for a big cooler that fits your cpu.

After that cooling is all about getting enough airflow to prevent overheating while keeping noise down.

Then look for quiet fans, the bigger the better. Noctua again are pretty good. However you also need to be running them at low voltage to keep the speed, therefore noise, down. There are a variety of fan speed controllers on the market, or cables which convert the usual 12v fan power points to 5 or 7v.

Your next problem is the video card fan. These can be incredibly noisy. I use a fanless card, but there are editors about for gpu card's BIOS settings which allow you to adjust the pre-set fan speed vs temperature curve. Lots of cards fan the fan up to full speed as soon as the card is doing more than idle. By adjusting the fan speed settings you can delay fan acceleration to when the card temperature actually calls for more cooling.

Finally there's the power supply fan. Another source of noise. Seagate make good fanless power supplies so long as you watch the total power drain. A case that puts the psu at the bottom can help keep the psu cool. Heat rises, and a psu at the top of a case is usually sitting in the hottest spot.

Then you need to test everything to find the lowest possible amount of fan noise. I do this by loading the cpu to 100% and keeping it there (prime95 is a useful tool for that) while I keep an eye on cpu temperature. So long as it stabilises for 15 minutes while below the cpu's maximum thermal rating I'm happy. This makes the cpu a bit hotter than normal at idle, but really pays off sound-wise. It's very rare for a cpu to hit a sustained 100% capacity, so running closer to the chip's rated temperature doesn't seem to cause a problem.

I do a similar thing with the gpu. I also check drive temperatures, though that's not an issue with SSDs. Suspending an HDD so it's isolated from the case, or even putting it in the case bottom on a layer of foam can do wonders for quieting them.

It's also worth trying case fans in different locations and voltages. The PC before this one had a single case fan which I found gave greatest cooling at lowest rpm when placed at the back of the case (where air usually exits) blowing into the case, with the top front 5.25" bay left empty and open for hot air to get out.

www.silentpcreview.com is a useful resource, especially the forums.

http://www.quietpc.com are a UK supplier of quiet parts, as are https://www.overclockers.co.uk. (no connection with either other than as a customer).

I have a Cooler Master Comos 1000. I choose it because it has sound insulation as well as 120 mm fans 4 of them. These are low noise fans yet move a lot air. The CPU fan is the loudest fan but is well contained by the case. This is not a inexpensive case but well worth the cost.
 
The overall noise from it is very low. A whisper. 

mettelus
Out of curiosity Jonesey, have you done an SPL check? Noise unto itself is subjective, so is difficult to understand the situation.

No, but I can do
 
Thanks for all the ideas so far chaps, didn't get chance last night to investigate further but intend to tonight.
 
FYI: graphics card is passive - no fan!

 
I have also used Noctura cooling and fans. They work very well and are quiet

I wonder how far away we are from being able to use this kind of tech for cooling:
 
http://smallformfactors.mil-embedded.com/articles/immersion-form-factor-server-class-systems/
 
e.g.
 
https://www.youtube.com/watch?v=CIbnl3Pj15w
https://www.youtube.com/watch?v=Z_X_hgtlJpA
 

A case that's intended to be low-noise is going to have variable-speed fans. If the fans are always running at high speed it could be an indication of inadequate airflow. This would not surprise me in a rack-mounted device, wherein larger, slower-moving fans might not be practical.
 
If possible, I'd situate the computer at the bottom of the rack so there's nothing producing heat below it, and leave a 1U gap above it. You can get rack filler panels that are vented. I suppose you could test this by measuring noise levels immediately after turning the computer on, and comparing that to a couple hours later. This could be accomplished by mounting your SPL meter on a mike stand so it's locked in a fixed position.
 
This is assuming the problem is really fan noise, rather than hard drives. The difference is that fans produce broadband semi-white noise that can be mitigated with acoustical absorption, whereas case rattles, resonances and hard drive spindles have to be treated mechanically rather than acoustically.
 
All of this could be moot, though. If the noise level as seen at your microphone is 30 dB or more below the ambient room noise, it's probably not affecting your recordings anyway. My computer is only 3 feet from my microphone and with 5 fans is by no means a "quiet" computer. But it's on the dead side of the mike and there is acoustical absorption between them. Even with the mike gain cranked, the fan noise picked up is down -60 dB or more, so I don't worry about it.

bitflipper
All of this could be moot, though. If the noise level as seen at your microphone is 30 dB or more below the ambient room noise, it's probably not affecting your recordings anyway. My computer is only 3 feet from my microphone and with 5 fans is by no means a "quiet" computer. But it's on the dead side of the mike and there is acoustical absorption between them. Even with the mike gain cranked, the fan noise picked up is down -60 dB or more, so I don't worry about it.

I agree with this, and is a good "practical" point. Because of this thread I checked my machine's SPL (simple phone app) and was 21dB with the machine off and 26dB with the machine running with the meter at "normal mic location." Simply rubbing my fingers together spiked it into the 35dB range (or even thing like shifting in chair (40dB), picking up/rubbing a piece of paper, etc.). It is easy to get fixated on something that we notice. With the same app my vocals exceed 70dB consistently, so the S/N ratio is pretty big and easily managed.

Agree with Jim, if the noise is increasing when you add the case, then there is probably some kind of sympathetic resonance happening. i.e. The case is amplifying whatever is causing the initial vibration.
Swapping out fans for different types/sizes/rotation speeds will help if it's a fan. Moving HDD's to a different mount will help if it's those that are causing the initial vibration. Placing a sound absorber between the computer and your recording position may also reduce the noise to an acceptable level.
Removing the case during recording would be a quick and dirty solution till you find out what's really going on.
Let us know what you end up doing as this is an issue for many home recordists and all efforts to reduce this kind of problem is always of interest.
Good luck.

The two things that look like fans at the top of the picture, are they not fans, but where case fans would fit?
 
If you have no case fans, I would suggest to fit some.  They're important to ensure good airflow within the case whilst the case is fitted.  I think you have a lack of airflow inside the case when it is fitted and temperature (and hence CPU fan speed) is building up over time.
 
[edit] If that's the OEM CPU fan, ditch it and fit a quiet one.  Also, a 500W PSU is perhaps a bit on the low side for the machine spec in your signature (assuming that spec is for the machine under discussion).

Running the computer with skins off can be risky because it can actually lead to overheating (as non-intuitive as that seems) by defeating the internal airflow design. (I say this even though my own machine has had its side panels off since day one.)
 
I once studied this phenomenon by monitoring heat sensors at critical points with skins off and on. This was in a server room where noise was not an issue but heat was. The machines ran cooler with fewer airflow paths, because the air could be directed over the heat-producing components rather than being dispersed.
 
The easiest solution, I think, is quieter replacement fans. They're relatively inexpensive ($20-30) and fit right into the space the old fans occupied.
 
 
 
 

Is that picture of the open case looking down on it as it is in the rack or sideways on? In other words, is the cpu cooler fan horizontal or vertical when it's in the rack? I'm just trying to get a mental picture of where the hot air naturally wants to go.

My gut thought is that a big, slow fan pushing air into the case might be helpful, so long as it's in the right place if it allows the cpu fan to be slower and prevents the psu fan kicking in. A similar cpu fan might help, depending on how noisy the one fitted at the moment is. Trouble is, not all fans and hardware advertised as "quiet" actually is, it's just a bit quieter than the small Intel and similar OEM fans that sound like vacuum cleaners when their speed ramps up. Gigabyte used to use a tiny fixed-speed fan on the m/b North Bridge chip which could be heard a few yards away.

The two HDD silencers look very much like ones I've used in the past. I found them a help with some HDD noise but not particularly effective at silencing seek noise and clicks or preventing a slow build up of initially low volume resonances from the motors that eventually could get quite noticeable. The most effective solution I found was to decouple the drives from the case by mount the boxes very loosely, either suspended by silicon bands with no screws directly linking them to the drive bay or placed on acoustic foam in the bottom of the case.

Another possibility for case resonance creation might be the fans creating beats between themselves which get magnified as they reinforce the resonance over time in a feedback loop. I had a problem last year when after an hour or two of running I'd start to get a regular slowly building "buzz.......buzz......buzz......buzz....." which was quite noticable in the room below the PC via the floorboards. The case side (a well-padded Fractal Design) could be felt vibrating.

The source turned out to be the case fan's bearing going a little rough and noisy (a long screwdriver makes an excellent stethoscope for isolating noise as any good mechanic will tell you, just keep hair, jewelry, sleeves etc. away from anything going round). The noise was so little at first I decided it couldn't be the cause of the problem, so ignored it and spent hours trying to isolate the source of the noise until in desperation I tried swapping the fan out, which cured the buzz immediately.

Poor fan mountings transmitting fan vibrations into the case or something connected to the case might be another thing to look at.

Not sure how well a fanless psu would handle that psu position. They usually have most vents in the top to let the rising hot air out. I'm using a Seasonic 460W one which handles the sig PC's requirements OK. It hase vents in the back (where the mains cable fits) and the top is a grille. It sits at the bottom rear of the case with the case fan extracting at the top rear.

A fanless psu also makes a case fan pretty indispensable I would think. One way or another adequate cool air has to be encouraged into the case or the hot air sucked out or allowed to escape.