24" iMac 2.4GHz Fan Speed When Idle

Discussion in 'iMac' started by Twisted T, Oct 17, 2007.

  1. Twisted T macrumors member

    Apr 19, 2004

    I recently purchased a 24" Intel iMac 2.4GHz. Forunately I haven't experienced any crashing or freezing problems like some users have, but what I have noticed is that the fan(s) seems to speed up quite significantly for no apparent reason when the machine is idle.

    When the computer is doing absolutely nothing sitting at 32 degrees, the fan speed increases from around 1200rpm up to about 3300rpm. This seems to happens every 10 minutes or so.

    Can anybody tell me if this is normal for the 2.4GHz 24" iMac? Or do I need to phone AppleCare to have it looked at? I used to own a previous revision 20" iMac and I hardly ever heard the fans kick in. It wouldn't normally bother me, but the fact that it makes a lot of noise is kind of annoying when I'm doing something simple, like writing in Textedit.

    I have updated to 1.1 with no joy. Currently I am using iStat Pro via Dashboard to read my system performace.


  2. Luap macrumors 65816


    Jul 5, 2004
    Hmm, I dont think that is normal.. No matter what ive put my new iMac through, the fan speed doesnt seem to increase at all. If it does, it certainly isnt an audible increase.
    It might be worth running your Activity Monitor app, and checking for any processes that could be gnawing on too much CPU and sending the system temps up.
  3. Twisted T thread starter macrumors member

    Apr 19, 2004
    Thanks for your input Luap!

    I called AppleCare this afternoon who advised me to reset the usual parameters - SMC, PRAM etc. with no joy. They then suggested I should erase and install the machine to see if it is a software problem or not.

    Unfortunately, I now believe it is a hardware issue. 5 minutes after reinstalling, the CPU fan kicked in and rose to 2800rpm and stayed there for a while. I will have to contact AppleCare tomorrow and arrange to send this unit back.

    Thanks again,

  4. vaimea macrumors newbie

    Oct 17, 2007
    Thank you TT for bringing this up .. my iMac is only 3 weeks old and it seems to have started doing the same thing .. keep us updated. Thank you, I'll be calling Applecare tomorrow ..
  5. arkay macrumors newbie

    Oct 7, 2007
    i suggest you download the smcfancontrol


    and see if it helps
  6. wackymacky macrumors 68000


    Sep 20, 2007
    38°39′20″N 27°13′10″W
    I'm beginning to suspect that Apple has a problem on its hands.

    I am having the same problem with my new 20" 2.4 GHZ new iMac. Was fine for a week, now one of the fans speeds upto 33,000 when idle (no processes running and CPU not doning any work) which won't resolve with a SMC re-set.

    There was a simular issue I believe with the older iMacs that was fixed with a firmware update.

    I've now seen of at least 25 people stating the new imacs are having issues with the fan speeds.

    I would suggest that every one who is having problems LET APPLE KNOW so they try and resple the problem.
  7. mattnedgus macrumors newbie

    Aug 28, 2007
    Hi, I'm having the opposite problem - my CPU fan won't turn on AT ALL!

    It's sat at 0rpm and the CPU/GPU temperatures are between 90 and 100degreesC!

    I've tried resetting the SMC as well as running smcFan Control - all with no luck.

    It's already been back for repairs twice and been away a total of 2 weeks in the last 2 months of owning it!
  8. rainydays macrumors 6502a

    Nov 6, 2006
    I find it odd that the computer will start at all without the CPU fan. That's not healthy for the CPU, nor the rest of the system for that matter.

    What did you have it repaired for? And why didn't they give you a replacement the first time?
  9. mattnedgus macrumors newbie

    Aug 28, 2007
    Sorry I took a while to reply rainydays - I haven't been checking my mail as much since my computer went in last week.

    It went in for repair for the graphics card originally (way back when!) - that had to be replaced because of the glitches/ artifacts on the screen that it produced.

    It then went back in a day later so they could clean the grease from the inside of the screen that had somehow been smeared over it.

    And on the third time (because of the fan stopping working) it went into the Apple Store instead of the repair centre and the fan was replaced - although this even took the store a week because they had ordered various parts 'just in case' it wasn't the fan...

    It's back now - I picked it up yesterday - and I'm keeping my fingers crossed it stays mended - 3rd time lucky :)

    There was no mention of an offer of a replacement and the computer was out of it's 14 days return to store warranty. The legalities of returning a product that turns faulty soon after purchase might be different however.

    I also made the mistake of installing a non-transferrable OEM version of Vista on there, which means if any 'wrong' part is changed, or if I get rid of the computer - I lose the licence! However, I have never known ANYTHING break quite so much as this has!
  10. katmcg macrumors newbie

    Nov 15, 2007
    imac fan noise

    I purchased an intel imac 20" on sunday, only to have it diagnosed as DOA yesterday. Fully replaced no problem, but the new one after startup had a loud buzzing noise (with blowing air coming out the back at the fan) which my first definitely did not.
    I reset the smc as advised from apple.com...still there, then turned up the screen brightness (it was on about medium).
    All noise has stopped...quiet as a mouse. Seem the noise only starts when the brightness is medium - low and high, there is no noise..
    So relieved, I was prepared to take it back tomorrow and resort to PC again :(

    However - should I take it back anyway and get repaired/replaced? I don't want quick rememdy for an underlying problem that may get worse/continue...?

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