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Noise from "silent" PC
Equipment:

Thecus N5200B NAS - ethernet cable - silent PC - firewire cable - Weiss DAC2 - Nordost Red Dawn XLR cables - Classe CAP2100 - Atlas speaker cable - B&W 804s (with Soundocity Outrigger)

PC:

Known as the "CAPS version 2" - a custom PC build designed by Chris Connaker of the Computer Audiophile website (www.computeraudiophile.com). Mine was built by Small Green Computer who have linked in with Chris Connaker (http://shop.smallgreencomputer.com/CAPS-20-CAPS.htm).

PC specs:

Origen ae M10 case; Jetway NF96FL-525-LF motherboard;  dual core 1.8 GHz Intel Atom D525 processor; 2x2GB modules of DDR2 667 from Transcend; 64GB Micro Center SSD drive; SOtM In-Line SATA Power Noise Filter; SYBA SD-VIA-FW1E1H PCI FireWire card (6-pin); Casetronic PW-12V5A-L5 60w power supply. More details about the CAPSv2 available here: http://www.computeraudiophile.com/content/...erver-caps-v20/. It is running Windows 7 Ultimate service pack 1 64-bit.

Problem:

The PC, supposedly silent, emits a noise. The noise can be divided into 2 components; a constant "crackling" noise - this is quiet though audible with the ear near to the case. It seems to fluctuate if the PC is being used (e.g. scrolling down through a website or starting a program). Moving the mouse causes slight fluctuations in it. The second noise is the main problem - a constant high-pitched emission; this noise starts when the firewire port is connected to an external device.

The noise only starts when Windows boots up to the main screen (it is not there on the BIOS screens). The noise is definitely coming from the PC unit itself and not anything external to it such as the speakers. Given the effect the firewire cable has on the noise, I ran some tests:

1. All equipment off & connected - no noise
2. Monitor on - no noise
3. CAPS on - no noise initially, then system beep, then some noise when the Windows logo appears, then the continuous noise when the Windows welcome screen and then desktop appear
4. Unplug monitor from CAPS - 1 second pause in noise, then resumes

5. Switch on DAC (connected to CAPS via 6pin-6pin firewire cable) - 1 second pause in noise, then resumes
6. Switch off DAC - noise continues, no pause
7. Unplug power from DAC - noise stops
8. Plug in power to DAC - 4 second pause, then noise resumes

9. Unplug firewire cable from CAPS - noise stops
10. Plug in firewire cable to CAPS - 2 second pause, then noise resumes
11. Unplug firewire cable from DAC - noise stops
12. Plug in firewire cable to DAC - 2 second pause, then noise resumes

13. Unplug/plug in ethernet cable to CAPS - no change
14. CAPS off - noise stops

I have opened up the unit to take a look inside. It's not really possible to isolate where the noise is coming from; the red circle in the photo below given my best guess but it could be wrong:

http://i49.tinypic.com/1fwew2.jpg

I tried disconnecting the SSD and booting up; I get a message saying "reboot and select proper boot device". There is no noise, though the noise only starts when the PC fires up into Windows anyway.

I looked into the firewire drivers on the PC. I tried a few different drivers that came with Windows, though they did not alter the sound. I then tried a driver from a third party (Unibrain - ubCore Firewire (Firewire 800 - IEEE 1394b) driver suite) and this significantly reduced the noise. However, when this driver was selected, the driver for my Weiss DAC2 seems to stop working:

http://i48.tinypic.com/2ltoy9h.jpg

The DAC2 is not recognised as long as the Unibrain firewire driver is being used. If I select the Windows legacy firewire driver and then disable the DAC2 driver, most of the sound goes away also (though not all of it). Of course I then cannot play music through the system as the DAC is disabled. I have tried a different firewire cable (4pin to 6pin) and used a 4pin to 6pin converter; this should cut the power leg of the cable. However, again no difference in sound.

When I run the Weiss DAC2 controller info program, it detects the OH 1394 Host Controller as: (1106) VIA Technologies, with chipset (3044) VT6307/6308. Finally, I tried connecting 2 firewire cables concurrently (there are 2 ports on both the DAC and the PC). This reduced the noise, though music will not play on the PC.

As you can see I have struggled with this for a while - any suggestions greatly appreciated! 
  • Last Edit: 15 October, 2012, 11:39:28 AM by extracampine

  • hlloyge
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Noise from "silent" PC
Reply #1
Remove firewire card and boot the computer, tell if the noise is still here.

  • phofman
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Noise from "silent" PC
Reply #2
Noisy motherboard is a rather common issue. Under load the on-board inductors deployed in the numerous step-down power supplies start emitting noise. Sometimes the cuprit are capacitors. Just google how people fight this noise https://www.google.cz/search?q=motherboard+...NNsvLsgbyp4DQDQ

  • washu
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Noise from "silent" PC
Reply #3
Your motherboard is a special one which has additional power conversion circuitry to generate the lower voltages normally supplied by a standard ATX power supply.  As the load changes on the firewire card the converters have to generate the power for the load.  Needless to say, the converters on that motherboard are designed with cost as their primary concern.  Not that I buy into the audiophile BS, but this is a rather poor and uninformed choice of motherboard for the use case.

Other than maybe using a USB DAC and putting less load on the converters, there isn't much you can do short of replacing the MB.

Noise from "silent" PC
Reply #4
Your motherboard is a special one which has additional power conversion circuitry to generate the lower voltages normally supplied by a standard ATX power supply.


I haven't seen a motherboard that lacked DC-DC converters for years and years. The root cause is CPU chips and other chips that require nonstandard voltages.  DC-DC converters almost always require some sort of energy storage device whether a coil or a capacitor or both. These parts especially the coils can easily become sound generators, whether by vibration of their coils or magnetostrictive effects on their cores. Capacitors can have dielectrics patricularly ceramics that function as acoustical generators just as easily.

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As the load changes on the firewire card the converters have to generate the power for the load.  Needless to say, the converters on that motherboard are designed with cost as their primary concern.


The desire to minimize the power dissipation of CPU and other chips has a consequence being that their power use becomes more and more dependent on what functions they are performing at the instant. This gets reflected back to the power supplies and there you are!

It may be possible to encapsulate noisy parts in sound damping compounds.

Just guessing, but this sort of thing properly applied might help:

http://www.parts-express.com/pe/showdetl.c...tnumber=268-266

Thing is that anything that dampens sound will also inhibit heat dissipation.

  • skamp
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  • Developer
Noise from "silent" PC
Reply #5
$1,500 for an Intel Atom PC that's supposed to be completely silent but instead emits annoying noises? Sorry, but you were scammed!
See my profile for measurements, tools and recommendations.

  • washu
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Noise from "silent" PC
Reply #6
I haven't seen a motherboard that lacked DC-DC converters for years and years.

This isn't the standard DC-DC converters that every motherboard has, though it does have those as well.  It's also the +5V, +3.3V, and -12V converters that are normally found in the power supply.  The external brick only generates +12V.  Thus the voltages needed by the firewire card (and everything else in the computer) are being generated by components on the motherboard instead of in the power supply like a normal computer.  Those converters have to fit a price point combined with the rest of the motherboard and are almost certainly of lower quality then those found in a dedicated power supply.

  • phofman
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Noise from "silent" PC
Reply #7
This isn't the standard DC-DC converters that every motherboard has, though it does have those as well.  It's also the +5V, +3.3V, and -12V converters that are normally found in the power supply.  The external brick only generates +12V.  Thus the voltages needed by the firewire card (and everything else in the computer) are being generated by components on the motherboard instead of in the power supply like a normal computer.  Those converters have to fit a price point combined with the rest of the motherboard and are almost certainly of lower quality then those found in a dedicated power supply.


I have a regular ATX MB which is very noisy too. Any DC/DC converter is a potential source of noise. IMO it is good (or bad) luck and the only way is to test and replace with another piece.

  • Trondis
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Noise from "silent" PC
Reply #8
$1,500 for an Intel Atom PC that's supposed to be completely silent but instead emits annoying noises? Sorry, but you were scammed!


I spent a lot of money last year to make my PC silent. It didn't work. So I have bought a Raspberry Pi ($35) instead for music playback. My harddisk is inside a closet, connected to a cheap NAS adapter (Patriot Gear Box - costed $45). This system is cheap and totally silent. It is also very convenient - I use XBMC that is remotely controlled from my phone.

  • garym
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Noise from "silent" PC
Reply #9
or pickup a Squeezebox Touch (< $300). Will play almost any sort of audio file, including FLAC at up to 24/96 natively (or 24/192 with free EDO app).  Music resides on computer anywhere you want (back closet, basement) as long as connected to local network and running Logitech Media Server software. Touch can connect to local network with WIFI or ethernet.  Touch has analog outs, optical outs, and S/PDIF coax outs (all live at same time).  Can use USB out to *certain* DACs if using Triode's EDO app.  And importantly, TOUCH itself has no moving parts and is silent.
  • Last Edit: 15 October, 2012, 07:45:26 PM by garym

  • Brand
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Noise from "silent" PC
Reply #10
At least with regular desktop motherboards you can sometimes eliminate noise like this by disabling some power states (C1, C3..) in BIOS.

I'm not familiar with Atom motherboards, but see if there's something like that to try.

  • googlebot
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Noise from "silent" PC
Reply #11
In 2001 I spent considerable efforts to manually eliminate my PC's noise in my student apartment. It was quite effective, but from the day I had implemented the changes, I started hearing my fridge, that I hadn't noticed until then.

Out of curiosity I turned off my fridge and noticed how the world outside the window immediately got louder. In the end, I lived happily with the moderate sound of my PC, the fridge, and the outside world and stopped worrying.

I agree with skamp, $1500 for a non-quiet Atom package: you have been scammed.


  • Porcus
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Noise from "silent" PC
Reply #12
Is that thing getting hot? If not ... a padded box?

  • Cegadede
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Noise from "silent" PC
Reply #13
I solved the noise problem by using an old eeepc 701 as my music player. I installed ubuntu server on it and mpd as the music player. The music is stored elsewhere on my home network and is mounted on the eeepc via nfs. As I didn't install a graphical user interface on the computer, I keep it's lid closed. Also, I've checked that music playing only uses less than 3% of the cpu, so it stays quite cool, allowing me to take of the cpu fan, wich made the pc completely silent.

I have it connected to a benchmark dac1 USB DAC and from there to a pair of denon POA-2800 power amps connected to a pair of Martin Logan's CLX ART speakers. 

The great thing about the eeepc 701 is that you can get one for less than US$50.00 and, for use in audio, it can be made totally silent by just removing the cooling fan (If you can hear it spining, I couldn't, but took it off anyway).

Noise from "silent" PC
Reply #14
I haven't seen a motherboard that lacked DC-DC converters for years and years.

This isn't the standard DC-DC converters that every motherboard has, though it does have those as well.  It's also the +5V, +3.3V, and -12V converters that are normally found in the power supply.  The external brick only generates +12V.  Thus the voltages needed by the firewire card (and everything else in the computer) are being generated by components on the motherboard instead of in the power supply like a normal computer.  Those converters have to fit a price point combined with the rest of the motherboard and are almost certainly of lower quality then those found in a dedicated power supply.


The quality of DC-DC converters in dedicated power supplies is often about as bad as they can get and live until next weekend.  ;-)

Seriously.

Their biggest advantage from a noise standpoint is often the fact that they are inside a fairly heavy tin box with a fan blocking the biggest hole.

Also, there is often just one SMPS in the PS box, with multiple secondaries on the transformer and individual filters for each voltage. That SMPS has a fairly large steady load on its 12 volt output. So, you don't have a SMPS with a highly variable load.

Noise from "silent" PC
Reply #15
Thanks for the replies all. I like the story about the fridge! 

Washu - are there any motherboards you could suggest? My DAC (Weiss DAC2) doesn't do USB - it has firewire, XLR, RCA and toslink.

I couldn't find anything about C1 etc powerstates in the BIOS.

Would getting a better power supply help? Or a power regenerator such as from PS Audio (http://www.psaudio.com/products/power/pw-power-plants/p10-power-plant/).

Thanks


  • mzil
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Noise from "silent" PC
Reply #16
I'm not sure if it will help with this particular poster, however I thought to pass on to all a way I significantly reduced the perceived noise of my PC tower: I moved it from on top of my solid wooden desk to underneath it, on a floor mat. Other than possibly needing to buy extension cords for the keyboard, mouse etc. (I luckily can just squeak by without them, but some of my cords are right at their limits), this simple, fast modification is free to try! 

People with less solid and dense desks that are more open than mine (where my legs/feet go) may not benefit as much as I do from this, other than the added travel distance of the sound waves causing some attenuation, however I highly recommend giving it go to all with noise issues. [Heavy padding of this open box area would possibly be even better still, but I found the amount of noise reduction from this simple step to be within my comfort zone.]
  • Last Edit: 16 October, 2012, 12:31:41 PM by mzil

  • washu
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Noise from "silent" PC
Reply #17
Washu - are there any motherboards you could suggest? My DAC (Weiss DAC2) doesn't do USB - it has firewire, XLR, RCA and toslink.

The problem with replacing the motherboard is the power supply.  Most motherboards, even mini-ITX ones will need a normal ATX power supply and not a 12V brick.  You can use a pico-PSU with your 12V brick to make it into a normal ATX supply.

Also, a different motherboard doesn't guarantee that it won't also have the same problem.  Jetway is more on the mid to low end of the quality scale, so an Intel or ASUS board may do better. 

Toslink would be my choice for the least possibility of noise.  No ground issues and very little power draw compared to firewire. 

Here is an example of a board with a Toslink out.  Not specifically recomending it, but it might work better for you.  It does lack VGA video, so that may be an issue depending on your display.
http://www.intel.com/content/www/us/en/mot...rd-d2700dc.html

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I couldn't find anything about C1 etc powerstates in the BIOS.

Look for anything relating to CPU power saving.  However, an Atom CPU uses so little power that I would doubt it makes any difference.
Quote
Would getting a better power supply help?

Maybe, if the 12V comming out of the brick is noisy it could cause issues.  I've had bad power supplies cause noise in analog computer audio, but I haven't encountered the issue in a while.
Quote
Or a power regenerator such as from PS Audio (http://www.psaudio.com/products/power/pw-power-plants/p10-power-plant/).

Almost certainly no, it would not help. 

  • Nick.C
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  • Developer
Noise from "silent" PC
Reply #18
Outside possibility: where is your modem / router / network switch in relation to your PC?

I ask as mine used to be next to my desk and caused a really annoying interference - until I moved it further away....
lossyWAV -q X -a 4 -s h -A --feedback 2 --limit 15848| FLAC -5 -e -p -b 512 -P=4096 -S-

Noise from "silent" PC
Reply #19
My router is in a different room to the PC, connected via ethernet cable.

Re: power supply - what is the difference between an "ATX" supply and a "brick"? Is one better than the other? If I use a pico-psu with the external power supply, would this help with the problem of the DC-DC converters on the motherboard?

  • washu
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Noise from "silent" PC
Reply #20
An ATX power supply is what most non-laptop computers use for power.  It takes AC input and supplies several voltages that computers need; +12V, +5V, +3.3V and -12V.  They connect to the motherboard using a standard 20 or 24 pin connector along with usually a dedicated 4 or 8 pin connector for the CPU.  A good quality one can have very good regulation with very stable output.  Even with these multiple voltages, all modern motherboards have DC-DC converters for supplying other voltages that things like the CPU need.

A "brick" in this context is an external power supply that usually supplies only one voltage, +12V.  The rest of the voltages must be generated from the +12V, in your case your motherboard does it with extra DC-DC converters in addition to the ones normal motherboards have.  My hypothesis in regards to your problem is that those extra DC-DC converters on your motherboard are causing the noise and are of lower quality then found in a good ATX power supply.

A "pico-PSU" is a special DC-DC converter that takes the +12V from a brick instead of AC and then generates the rest of the voltages that a normal ATX power supply would create.  It is basically the same as the extra DC-DC converters your motherboard has, but designed to plug into normal motherboards that lack them.  They are hopefully of somewhat better quality, I have a couple and they make no noise that I can detect.

Your motherboard is different then most and expects only +12V from a brick.  It in fact cannot use a normal ATX power supply (without some hacking) or a pico-PSU.  It does not have the connectors needed to hook up a normal computer power supply.  My comment about the pico-PSU was for use with a replacement motherboard that has the normal connectors.  You could use any normal ATX power supply with a normal motherboard, but your small case limits the size so a pico-PSU would fit.


  • scuzzy1
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Noise from "silent" PC
Reply #21
Would it be possible to return the computer for (preferably) a refund or replacement?

Just my opinion, but while the enclosure looks pretty roomy, replacing motherboards (and likely other components) in that small of an enclosure, can be surprisingly difficult if you have no experience with building a computer.

  • nagual
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Noise from "silent" PC
Reply #22
I recommend to anyone who desires to lower PC noise floor:

http://www.pcmus.com/power-grounding.htm

  • pdq
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Noise from "silent" PC
Reply #23
Why are some people misunderstanding the OP's problem? This is not an issue of noise in the audio output of the PC, the PC itself is emitting audible noise from within the case.

Noise from "silent" PC
Reply #24
I asked Andrew of Small Green Computer for a refund or replacement though he did not oblige.

Interesting board washu, I'll take a look into that. I might look into trying a different brick power supply, though I don't imagine that it will make much difference.