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User profile for user: No 1 London
No 1 London Author
User level: Level 1
5 points

iMac making loud fan noise

The iMac has unexpectedly started to make a loud fan noise. How can I resolve this or is it a case of getting it back for repairs?

It's a 2007 Intel Core2 Duo iMac7,1 2.4GHz. It's less than six months old and has just been back to the Apple Store for repairs.

It now starts to make a very loud fan noise: CPU Drive 1200rpm, Hard Drive 1200rpm, Optical Drive 100rpm.

Then the CPU Drive fan goes up to 3400rpm.

I have tried resetting the SMU and also removed power and USB cables, waited and restarted. It still makes loud fan noises even while doing low performance tasks like writing email or browsing the web.

iMac, Mac OS X (10.5.2), 2007 Intel Core2 Duo 2.4GHz iMac7,1

Posted on May 24, 2008 4:45 AM

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7 replies
User profile for user: den.thed
den.thed
User level: Level 9
76,846 points

May 24, 2008 9:58 AM in response to No 1 London

{quote:} I have tried resetting the SMU and also removed power and USB cables, waited and restarted.{quote}

Hello No 1

Try resetting the SMC again, the reset for the Intel iMac's is a little different than the SMU for earlier systems. Have a look at step 4. in the following link:

http://docs.info.apple.com/article.html?artnum=303446-en

Then if that fan still runs amuck, you probably have a faulty CPU temperature sensor and it needs to go in for service.

Dennis
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User profile for user: No 1 London
No 1 London Author
User level: Level 1
5 points

Jun 8, 2008 2:21 AM in response to den.thed

iMac is still making loud fan noise. Apple Repair has serviced it but has not been able to solve it.

The fan goes to 3400 rpm and CPU A temperature to 120°C. It does calm down intermittently but frequently goes up to that speed. When the fan is below 3000 rpm it is tolerable but above that level it is just too noisy.

Apple Service says sensors and hardware are OK. Apple Hardware test (pressing Cmd D on startup) returns good results.

I have tried running Console and Activity Monitor to see if it could be software related but still haven't managed to find a solution yet.

Any other ideas?
Thank you.
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User profile for user: den.thed
den.thed
User level: Level 9
76,846 points

Jun 8, 2008 10:06 AM in response to No 1 London

{quote:}iMac is still making loud fan noise. Apple Repair has serviced it but has not been able to solve it.{quote}

Intermittent problems are more difficult to solve, but that still sounds like a bad sensor or worst case the CPU's temp. is spiking! Either way it needs to be looked at by someone that can properly diagnose and fix it.
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User profile for user: Koomin
Koomin
User level: Level 1
0 points

Jun 8, 2008 10:15 AM in response to den.thed

Ive had the same problem for months now. Ive delivered my computer for service two times. After the second time it seemed to be ok, but now after about a mont, the fan noise is back. The fan gets turned on, and it never shuts off. The computer can be on the entire night, without anything to do, and still the fan runs.

The two first times i got an error when i ran a hardware test, but now nothing comes up. I fear that i have to call Apple again, but its been over 90 days, and Apple has a HUGE charge if you call support now. The sollution is offcourse to buy Apple Protection Plan.

sigh
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iMac making loud fan noise

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