Help with 20" C2D noise issue

Discussion in 'iMac' started by jimbama, Oct 5, 2006.

  1. jimbama macrumors newbie

    Oct 5, 2006
    I know that the noise issue with the new imacs has been discussed to some extent on this forum, but I wanted to see if anyone could help me out with a more specific question.

    Basically, I just purchased a 20" core 2 imac, and the noise from my machine is a bit more than I had expected- nothing crazy, but a constant hum/whirring that I am assuming is the fan or hard drive (definitely not the power supply).

    I've seen other people here describe their imacs as almost silent. I guess I was just wondering what exactly that would mean- my point of reference is my old 500mhz G3 imac, so i'm not sure what this new one is suppoosed to sound like. In my case, if I'm standing about 5 feet away I can still hear the noise.

    Anyway, any help would be greatly appreciated- i'm just trying to figure out if it's worth bringing in to the apple store, or if i'm just nuts. Thanks in advance- this is my first post here, I certainly hope to return the favor in the future.
  2. Macmadant macrumors 6502a

    Jun 4, 2005
    My 20" also has a constant hum which get's louder the longer the machine is on, but it reaches a maximum noise, i can here it when standing away from the machine or when i'm sat away from it
  3. Thrash911 macrumors 6502


    Sep 14, 2006
    Randers, DK
    If it is the humming noise, then it is propably related to the brightness of the screen. Try to listen for the noise, while turning the brightness up and down (F14 + F15). The noise should (almost) disappear when it is most bright.

    Then dim the screen with Brightness Control 1.0.4. That is perfect for just general work in OS X. But if you start games and such, it might revert to the original brightness..

    Personally, I try to get used to the humming noise. Hoping it won't bother me so much over time..
  4. Iker89 macrumors member

    Sep 20, 2006
    My iMac has a slight "popping" noise every once in a while. Anyone know what thats caused by?
  5. volk macrumors member

    Oct 2, 2006
    Add me to this list. After two weeks of flawless operation, my 24" iMac last night started displaying a fan noise. It seems to be coming from what I believe is the video card (on the left behind the screen). It is loud enough that it can be heard and recorded by an audio editor through the built in isight. I am hoping it goes is annoying enough that I might get it repaired. Also strange to me is that sometimes when waking from sleep or when first starting up, the fan revs up to max speed for just a moment and then returns to normal.

  6. The General macrumors 601

    Jul 7, 2006
    Oh noes! You mean to tell me that your computer doesn't have a magic cooling system that gets rid of all the heat without making a sound?:rolleyes:

    I thought we all had those... :rolleyes:
  7. volk macrumors member

    Oct 2, 2006

    While I appreciate condescencion as much as any other person looking for help, I don't expect my iMac to be silent. This is a NEW problem. It started making this noise last night, something it hadn't been doing up to that point. It is about as loud as the P4 tower I use in the office, which is quite loud. In addition, my sleep light has stopped blinking, and now remains lit solid when asleep. I have not experienced any real crashes or anything, so I haven't really troubleshot it yet, but it is definitely annoying. I am concerned that perhaps the logic board is going bad. The noise is present from startup on and is consistant, but goes away when the computer goes to sleep. Noise is critical on the iMac, because the fans are at head level, not under your desk like you can do with a tower.

    I will try some diagnostics first before I take it to Apple. Maybe a PRAM reset would fix this?
  8. todd2000 macrumors 68000

    Nov 14, 2005
    Danville, VA
    I've had my 17" iMac for a month and a half, and have never heard a peep from it. No fans or anything. Im not convinced it has fans :). I would say if it just started, it couldn't hurt to bring it in to the Apple Store and get it looked at, it's free after all :) The worst they can do is tell you your crazy, and tell you to go away. LOL, or mabye it really is broken and they will fix it or something.

    EDIT: Just realized its a Core 2 mabye it just has more fans then my Core Duo, Im not really sure.
  9. volk macrumors member

    Oct 2, 2006

    It was virtually silent before now. I have been checking the Apple site for information on resetting the SMC. I will do that first and see if it fixes. That would explain the the sleep light and fan noise if it is corrupted. Unfortunately for me, the nearest Apple store is 3 hours away from me...not really something I want to do if I don't have to.
  10. wakerider017 macrumors 68000


    Sep 20, 2006
    US of A
    Hey, when my computer screen dims it hums...

    Whats up with this?

    Also when screensaver is on it makes a ticking noise... (is this coming from the speakers... Like supposed to be a count down before it goes into sleep?)
  11. jimbama thread starter macrumors newbie

    Oct 5, 2006
    Same thing for me as far as waking it up from sleep. In fact, everything you wrote seems exactly the same as what i'm experiencing, except that mine is only a week old. Problem is, I can't remember if it was silent or not at first, but I know that the noise didn't occur to me until after a few days. If you have any luck with resetting the PRAM, SMC, etc., definitely let us know.

    As for me, I think this is enough to warrant packing the damn thing up and bringing it over to the apple store- luckily there is one about 5 min from my house. I'll report on any progress. thank you for the replies!
  12. panurge macrumors newbie

    Oct 8, 2006
    I think I'm having the same problem with my iMac 20" Core 2 Duo.

    First I want to make some things clear, which always seem to show up when I describe my humming/buzzing.
    • This is not a display issue. 24" iMac's display-humming has nothing to do with this noise. My 20" iMac does not stop buzzing even if I shut the whole display (i.e. put it to sleep)
    • It's not a vibration issue. I mean it does not vibrate (resonate) with something outside the iMac. I've tried my mac on different tables, put mouse pad under it, and even used it on floor. It did vibrate on my other table, and it stopped when i put my mouse pad under it. Anyways, the vibrating sound was different from the buzz.
    • I realize the iMac is not supposed to be absolutely noiseless, and it is normal to hear the fans blow when you put your ear close to the air intakes. I can hear this blowing, but I (sadly) hear an annoying buzz too. And I hear the buzz everywhere in the room, not just my ear next to the machine.
    • It does not come from hard drive. I also shut down the hard drive to test this (I ran hdparm -Y /dev/sda on Knoppix)

    My buzz, as i prefer to call it, is constant. It seems to come from the hole above the power socket. The noise begins when I turn on the power, and it does get a bit louder the longer the machine is on. It is loudest when I play Quake 4 (demo). Don't get me wrong if I keep using the word loud. Actually it is not that loud, but it is very distinctive and thus hard to ignore. One of the main reasons I bought iMac was the silence. It is supposed to be silent. Let me quote some reviews: on 17" iMac on 20" iMac
    Yeah, I only wish. This thing is really annoying. I think I'm gonna switch back to my PC, which is louder, but in a more pleasent way. It does not buzz at all, the fans just blow loud. Lucky me, I still can return this noise-box to Apple Store.
  13. Macmadant macrumors 6502a

    Jun 4, 2005
    Well you've hit the nail on the head, this is the exact problem i have a buzzing noise, constantly, even when the display is asleep (well there's no noise when the actual computer is sleeping) i hope apple can resolve this sound it's very annoying and gets louder after a period of time of the computer being on, i don't think it's fans if it were and it would be a lot less annoying. i can even hear it when i have the T.V on sometimes :(

    P.S. Why doesn't the new C2D Imacs have fan speed sensors, this is stupid seeing as though the iMac G5 had them
  14. orangezorki macrumors 6502a

    Aug 30, 2006
    I wouldn't dismiss the fans too quickly. They do ramp up on the intel iMacs, and that would explain why it is most noticable when you are doing something processor intensive.

    While a normal fan will just make a bit more of a whoosh when working more, if slightly out of whack, it can rub or vibrate, causing these noises which can be annoying even if not that loud. I've already sent a 24" iMac back because of it, and hope that the replacement arriving soon doesn't have that or any other issues.

  15. panurge macrumors newbie

    Oct 8, 2006
    My best guess is also a loose / badly mounted fan, which resonates with the iMac's case etc.

    I actually took the machine to a local Apple repair place, but soon I learned, that the repair would take over a week (possibly even more), and also considering that the noise is not so loud, that they might have dismissed me as a paranoid person, who complains for nothing, I fetched it back, and today (monday) called Apple Store for a return arrangment. (Sorry for the long and confusing sentence :) )
    Anyways, the girl in Apple Store suggested a replacement, but I refused, since it's possible that this is a larger problem and I would get a replacement with the same defect. So now I'm waiting for my money back and then I'm going to buy an iMac from a local store. Of course this way it will be more expensive, but at least I can see and hear what I'm going to buy.

    So what's the moral of the story?
    No two iMacs are the same.
    Don’t buy a pig in a poke.

  16. volk macrumors member

    Oct 2, 2006

    Here is an update:

    I have found that the proceedure for resetting the SMC is to simply shut the computer down and unplug the power cord and any other peripherals (keyboard, mouse, etc...) from the iMac. You should wait at least 15 seconds, then plug everything back in and start as normal. It would also seem that if you shut down the computer for an extended period of time, it has the same effect.

    I did not perform the SMC reset, but instead went out of town for a couple of days. I shut the iMac down before I left. When I got back, I booted up and it has been acting normally since. Sleep is working properly, and while I occassionally get a short fan rev when waking from sleep, there isn't any loud fan activity persistantly running in the background. It appears that the SMC controls several power and fan settings.

    I do have the screen brightness hum that everyone is complaining about, but with any noise going on in the house at all, it becomes hardly noticable. I have turned my brightness up a bit to minimize the effect...but unless it worsens, I will likely not bother with it. It is still more quiet than a fan in a standard PC box.

    Reset your SMC and then let me know your results!

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