Macworld Forums: New iMac loud fan noise - Macworld Forums

The new iMac, 2.4Ghz, now has the fan running a high speed. Quite noisy. Today is the first time the fan came on. The iMac is one month old. I repaired permissions and rebooted several times but the fan is still on. The room temperature is 65 so that is not the issue. I shut down the computer at night and startup in the morning.
I am running the hardware test now, unplugged every thing except the keyboard and mouse and restarted with "D" key pressed down.
Any thoughts??

Hi-
It could be a faulty temperature sensor. Since your iMac is a month old, it's still under warranty, so take it to an Apple Store, or contact Apple Care, and have it checked out. Good luck.

The hardware check was OK. Just got off the phone from Apple help. Removed the power cord from the back of the iMac waited 15 seconds and plugged it back in. Solved the problem! Go figure??

That's good to know. Perhaps there's an automatic power reset on the new iMacs when they're unplugged for a while. That would be nice for those of us who have had to reset the power manager on our machines.

To clarify the obvious, the iMac was shut down all devices were unplugged except the keyboard and
mouse then the power cord was unplugged from the back of the iMac.
What is interesting to me, when the iMac is shut down every evening a power strip is turned off that cuts off power to iMac, printers and external hard drives. So there is no power available every night? But unpluging the cord from the back of the iMac worked??

Glad to hear your fan problem is fixed. It's interesting to hear about some of the high-tech solutions recommended by Apple. Good luck. /forums/ubbthreads/images/graemlins/grin.gif

hi all, i'm from Singapore and encountered similar problem of LOUD fan noise on my new iMac Intel 20" (less than a month old) 2 weeks ago. It happened when i switched on the Mac, after I came back from work. The fan noise was unbelievably loud (like a vacumn cleaner!) . Under normal circumstances, you can't even hear any fan noises.
From the back of the horizontal vent,i can feel air gushing out ! I tried to off it and restart...no use.
Here's what i did to "solve" . I shut down and went for my dinner.
Half an hour later, I switch the Mac on and the fan noise disappered !
Since then, touch wood...it is okay.
I did nothing different....Strange !!
Hope this help if anyone else encounter this problem.
Switch off and take a break ....an restart...before you drag the whole iMac to service centre.
Cheers
Martin

Hi, my iMac Intel 20" does the same thing. Sometimes, when I turn it on (and don't hold the power button until hear the beep) the fans go crazy!!!! Strangely, this only happens when I don't wait for the beep to release the power button.

And the problem is: when I use BootCamp and the fans are crazy, Windows don't start. MacOS X runs OK (if you can ignore the noise and the "tornado" on the back of monitor..). Go figure....

Anyone has the same Windows problem??? It only crashes at startup when the fans are like that, so i guess it's no a software problem.

Hi
This should help you understand a bit more. It's also the same process for the Intel based Mac mini, iMac G5s, and Power Mac G5 ( Late 2004 ). Once I started reading your post I realized what Apple was suggesting and why, and remembered that was the new way of a PMU like reset and that's what I had to do to my iMac G5 ( iSight ) once.

Dude I want to thank you so much. I did exactly as you said and puff the fan noise went away. I was going nuts.

Hi, my iMac Intel 20" did the exact same thing today. The fans went crazy

This is the second time it happens in one week. I have installed Windows XP by using BootCamp.

Windows did not start or took very long time to boot, could not wait. I tested the hardware by holding down the "D" button and no fault where found. Mac OS worked.

After several restarts with power loss it suddenly worked...

Does any one know if there are a software fix for this?

/Magnus

Hello. Just purchased a 24" alu iMac refurb (2.4ghz 2k7 model.) Is it normal for the fan to run 24/7?

It's still fairly quiet. It just runs constantly at 1200 rpms (cpu and hd fan) and 700 rpms (optical fan,) and is loud compared to my old 20" aluminum iMac 2k7 refurb which was dead silent with no fan noise at all.

After some internet searching it looks like some say their 24" iMacs are dead silent while others say there is a slight fan noise to theirs.

Apple had me power it off, unplug and hold down the power button for 20 seconds, but that didn't do anything. Apple tech support said the fans shouldn't kick in at all upon bootup if the iMac has been off for a few hours. But the fan always seems on.

A friend says he puts his ear up to his 24" alu iMac and hears nothing.

What say the MacWorld 24" alu iMac owners?

Mine is virtually noiseless, although I can hear the fan if I put my ear to the top edge. In fact the top edge gets very warm, and sometimes I wonder if the fan should be more active. The hint about disconnecting the power might be useful if it starts playing up in the future.

The noise is just nothing compared to my old emac, which produced an unwanted white noise background throughout my working day.

I have purchased a new iMac 24 inch (mid 2007 model; 2,4Ghz; upgraded to 4Ghz of memory) six months ago. Everything seemed fine until about a month ago when I have noticed a rattling noise coming out from the bottom left (where memory slot is located) which drove me nuts. I have tried to fix this problem by restoring the SMU (System Management Unit) however; this option did not resolve this issue.
Then, I have decided to run Apple Hardware Test from the internal hard drive by restarting my computer while pressing and holding the 'D' key on the keyboard during startup. (http://support.apple.com/kb/HT1883). This process was completed in a few minutes and once I have restarted my iMac, very annoying rattling noise was GONE!