Possible coil whine in my nMP

Discussion in 'Mac Pro' started by tylmad, Feb 5, 2014.

  1. tylmad macrumors newbie

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    Feb 25, 2009
    #1
    Just got my nMP the other day, and noticed a faint noise coming from inside. Not like a fan, but more like a scraping sound. When it's quiet in the room, the sound slowly begins to massage my brain, and it feels more and more high pitched. This really drives me crazy.

    I tried benchmarking the machine, and noticed that the sound from inside changed. In "Heaven" the noise became higher, but only in certain parts of the test (!) When I chose to walk around freely within the benchmark, and faced objects that seemed to have complex textures, the sound became larger, especially when looking at the ground.

    The sound is similar to this:

    https://www.youtube.com/watch?v=1FdCKZ8qaUU

    I spoke to Apple yesterday and today, and they will send me a new machine as soon as possible. They were really nice on the phone, great support! I just hope that I'm not overly sensitive to sounds and that this is not something that occurs on several machines.

    Anyone else that hears something similar?

    My machine: 4c, 32GB, 512GB, D500
     
  2. tylmad thread starter macrumors newbie

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    Feb 25, 2009
    #2
    ...and it continues

    Just thought that I could share my experiences here, if someone else hears something from their nMP.

    Had some friends over to listen to the machine, and they confirmed that the sound was indeed irritating, if it was silent in the room (and it normally is).

    Got a replacement machine today, same specs (4c, d500, 32GB, 512GB), same noise... Called Apple again and I will now take my new nMP (since I now have two of them) to an Apple Store tomorrow and they will take a look at it.

    Right now I'm thinking that it might be something related to the d500:s, and I think my next step will be to order a new machine with d700:s instead and cross my fingers! I'm really sensitive to constant, however silent, noises, but hopefully I've just been unlucky.
     
  3. Gav Mack macrumors 68020

    Gav Mack

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    #3
    If it's like the audio on that video that's most likely a coil in the PSU making that noise and not from the GPU cards.
     
  4. goMac macrumors 603

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    Apr 15, 2004
    #4
    Have you tried plugging into a different outlet or maybe plugging it in at a different location?

    Two units having the same issue is suspicious. I wonder if it's some sort of issue between your wiring and the Mac Pro.
     
  5. Anim macrumors 6502a

    Anim

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    #5
    Good point.

    Recording studio's often install all manner of devices to remove buzz, hum and odd sounds from cabling and power.

    e.g. http://homerecording.about.com/od/homestudiobasics/a/Recording-Studio-Power-Conditioning.htm

    Also, are you using any third party wireless devices? For example a wireless mouse can cause interference which is picked up.

    And as goMac said, try plugging your nMP into a different socket, maybe at a different house just to rule out that it isn't your wiring.
     
  6. tylmad thread starter macrumors newbie

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    Feb 25, 2009
    #6
    I tried capturing the sound with my cell phone: (I put the phone on top of the machine)

    http://mikael.tylmad.com/mac_pro_noise.m4a

    In this clip I started the Heaven benchmark, and about 17 seconds into the clip I turned the camera up towards the sun in the sky.

    Both machines are creating that exact "hissing" sound in the Heaven benchmark and it seems to be in exactly the same places as well.

    There is also another type of hissing sound that occurs when I close the benchmark and you see credits on the screen, also the same on both machines.

    But the worst part is that there is a constant faint hissing sound, not so bad as the one in the clip, but it's there.

    ----------

    Just tried plugging it into a UPS, and let the UPS work on it's own, but it made no difference.

    I'm from Sweden, so we have 230 volt +6/-10% 50 Hz, I'm no expert in this though, but perhaps it could make a difference to the PSU and create this problem for us here on the other side of the world?
     
  7. Gav Mack macrumors 68020

    Gav Mack

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    #7
    Just had to rewrite the reply after reading that! No it shouldn't make a difference with your mains, it's pretty much euro standard apart from us being 10v higher in the uk.

    Was the ups a pure sine wave one like the apc models? If so you will have to do the laborious process of elimination by unplugging all the devices connected to the nMP and testing the audio. Also unplug as many electrical items out of their plugs on your current ring main. Change the audio cable, speakers if possible, separate data and power cables away from each other.
     
  8. Anim macrumors 6502a

    Anim

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    #8
    Apple state that the new mac pro electrical requirements are:

    So you should be fine. But, maybe you can hear that 12db??
     
  9. tylmad thread starter macrumors newbie

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    #9
    The fan is definitely hard to hear when idle, from my work position I can't hear it at all. But this hissing sound is easy to hear. And when it changes, during graphical stuff, it's even easier. Even in idle mode there is a constant hissing, sort of flickering, noise.
     
  10. tylmad thread starter macrumors newbie

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    #10
    I used a line interactive UPS, a model I like from APC actually, but at this point I don't think the power is an issue.

    I tried to run and listen to both machines with only the power cable connected. I unplugged all USB-cables and the monitor after positioning myself within the Heaven Benchmark, and the sound wouldn't change, no mater what I did to the Mac Pro. The only thing that changes the hissing sound is moving around in the 3D environment.

    It will be interesting to hear what the apple-people say when I see them tomorrow. Personally I would like to run the machine with the case of, and use a real microphone to pin-point the source of the sound.
     
  11. Gav Mack macrumors 68020

    Gav Mack

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    #11
    Have you switched the speaker set and cables for another type to eliminate that being the culprit and what kind are they - connected via the 3.5mm jack?
    Make and model of monitor and what type of video cable connects to the can, direct cable or through adaptors?

    Changing all of those or ruling them all out if I was me I would be stumped and would be calling my friend to bring his incredibly expensive Rohde and Schwarz analyser round!
     
  12. tylmad thread starter macrumors newbie

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    Feb 25, 2009
    #12
    I tried running the machines with only the power cable, all other equipment powered down and not connected, it made no difference to the sound. So, only one cable going from the nMP, the power cable.
     
  13. Anim, Feb 14, 2014
    Last edited: Feb 14, 2014

    Anim macrumors 6502a

    Anim

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    #13
    So, based on your process of elimination and the fact that it does it on both machines concludes:

    a) A fault on both machines, e.g. Coil whine.
    b) Some kind of EMF interference caused by your household electrical supply.

    I could say that you have superb hearing but as you got friends around to confirm it that is less likely the cause.

    There is nothing else to test is there?

    I suppose you could take out some ram but doubt that would prove anything.

    I assume you have tested outside your own household?

    Does it make the sound at the disk selection menu (hold option key down) or only when Mavericks has started?

    Have you tried tilting the machine onto its side, did it have any effect on the sound?

    Also, just read this on GPU coil whine. Quite interesting and explains the characteristics of the sound.
    http://www.overclock.net/t/1094728/possible-fix-for-coil-whine
     
  14. handheldgames macrumors 65816

    handheldgames

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    #14
    It sounds very similar to the noise my gigabyte 7950 makes. For a sanity test, make sure you have no halogen based lights engaged on the circuit.

    Try running the tests on the OpenGL extension viewer from the App Store and see if the problem exacerbates.
     
  15. tylmad thread starter macrumors newbie

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    Feb 25, 2009
    #15
    The faint hissing sound starts immediately when I start the machine, and tilting it to it's side doesn't seem to affect the sound in any way.

    ----------

    No halogen based lights. I tried the OpenGL extension viewer, and the hissing sound didn't get worse at all, it stayed at the "idle" level. So the Heaven benchmark is better at making this sound escalate. I tried toggling various settings in Heaven just to see if it I could find a particular setting that makes everything worse, but I couldn't. Maybe it's related to textures and the ram on the cards?

    Another thing that's strange is that when I quit the heaven benchmark, the sound changes into a much more high pitched tone during the end credits.
     
  16. FrankHahn macrumors 6502a

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    May 17, 2011
    #16
    What kind of display are you using? My Apple Cinema Display sometimes makes a noise of this sort.

    I originally thought the noise came from the Mac mini. I eventually figured out that it was from the ACD.

    If I unplug the ACD overnight, the noise can go away for a period of time (from several hours up to several days).

    I have been thinking of getting rid of this ACD. But I have not found a proper replacement.
     
  17. Gav Mack macrumors 68020

    Gav Mack

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    #17
    Along one of the lines I was thinking when I asked for the monitor type and cables, I have heard noise on a system before and pinned it down to RFI leakage through the video lead/adaptor at higher resolutions. Not on an ACD or even on a Mac either, but changed the dual link dvi cable for another much better quality cable with a pair of ferrite cores either end and the noise was gone.
     
  18. saschke macrumors 6502

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    Feb 2, 2008
    #18
    Just chiming in to state that my nMP is making the exact same noises. There's even a small hissing whine when it's idle. Just audible enough that it irritates me... (I'm sensitive with noise). I wonder what I should do, I have bought AppleCare with the machine and ponder creating a preliminary support ticket.
     
  19. tylmad thread starter macrumors newbie

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    Feb 25, 2009
    #19
    I'm sorry to hear that! The latest news for me is that I will return my nMP and the one I got as a replacement, since both had the noise. I hope that the noise is related to the components that I selected (4c, D500, 32GB, 512GB), because I have now ordered a new one with different specs (6c, D700, 32GB, 512GB). If that one also has the noise, I'll probably just try to live with it, and try to hide the computer behind something, just to mask out the noise. But I really, really hope it won't come to that!

    What specs did your nMP have saschke?

    Edit: Now I see you wrote your specs, so never mind :)
     
  20. saschke macrumors 6502

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    Feb 2, 2008
    #20
    Let me know how it goes for you, I will contact Apple in the coming days about it.
     
  21. dukk, Mar 4, 2014
    Last edited: Mar 4, 2014

    dukk macrumors newbie

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    Oct 18, 2012
    #21
    Just chiming in here, I have the same issue, 6c, 32gb, d700, 512gb, I'm going to try whatever I can to see if I can find a workaround/ fix, but also very curious about how it works out for you guys.

    tylmad how did you convince apple to send a replacement, if you don't mind sharing your magic trick :)

    I have Apple care on the machine, but the initial response is I would have to turn it over to a service center (with 10-14 day service times).

    kind regards,

    dukk
     
  22. saschke macrumors 6502

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    Feb 2, 2008
    #22
    Hey Dukk, Tylmad

    I have just talked to two peeps at Apple, first, someone from technical AppleCare support, then to a nice gal from After Sales. I've tried to stay calm and friendly and argued that I know that many people cannot hear something like coil whine but I'm getting headaches from the sound nevertheless. They've acknowledged that these things happen and suggested two options plus a third one that won't happen (cancel the purchase):

    a) I had suggested that maybe the whine is a 4C problem only and would be willing to try to get a processor upgrade. They actually suggested that I take it in for an upgrade to a local reseller and would evaluate if they chip in for half the cost or something later.

    b) They would send me a new machine and she would elevate the problem so I can keep my old machine for longer than 10 days before the new one arrives.

    After reading that you have the same problem with the 6C version (@Dukk) I ponder just asking for option b) and see if another machine exhibits the same noise.
     
  23. dukk macrumors newbie

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    Oct 18, 2012
    #23
    option b sounds like a good plan saschke, no loss for you, I'm going to see what happens to you two and maybe try the things tylmad already tried, just because (try and isolate and "prove" the issue).
     
  24. tylmad thread starter macrumors newbie

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    Feb 25, 2009
    #24
    Sorry, no magic trick :) Just told them that it whines, and they told me that it shouldn't. But now I'm concerned, since my new order was an exact match as your "wining tube" :(
     
  25. BJonson macrumors 6502a

    BJonson

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    Aug 26, 2010
    #25
    My thinkpad makes this exact same noise. The fix is to turn off CPU low power state in the bios. Intel CPUs sometimes make this sound when they are trying to lower the voltage in the multiple cores. The fix works on the thinkpad but not completely, it lowers the sound to a very quiet undetectable level but its still there. Only seen this in sandy bridge and ivy bridge though. I think the nMP uses ivy bridge right? I know its not haswell.
     

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