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Fans going crazy, CPU 100% idle


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#16 OP .Neo

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Posted 30 September 2012 - 12:23

Here's an interesting blog post about the issue. You probably have already read it since it was in the first 10 results of a google search but i still post it just in case.

http://gigaom.com/ap...lion-heres-why/

Spotlight reindexing doesn't take days or weeks.


#17 Pedro3

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Posted 14 October 2012 - 12:24

Did you try to install Lion or Snow Leopard? Just to have sure that the problem is in ML

#18 Hum

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Posted 14 October 2012 - 12:40

Maybe this helps:

http://www.hddfancontrol.com/

OR:

Symptoms

After plugging in the iMac and turning it on, the fans (blowers) may be noisy and appear to run at full speed. In this event, shutting the iMac off and turning it on again wouldn't fix the issue.

Resolution

If you press the iMac power button while you are inserting the power cord, the iMac will enter a mode in which the fans (blowers) run at full speed. In order to correct the issue, reset the SMC and then start the computer by pressing the power button after the power cord has been fully inserted.

The iMac should now start up and operate as expected.

http://support.apple.com/kb/TS1433

AND:

First download and install smcFanControl 2.2.2. Set it up to provide (still quiet) minimum fan speeds of 2200 rpm for the HD and 2800 rpm for the CPU, leave the Optical Drive fan at 600 rpm to minimize dust accumulation (or just tweak it up if/when you will be using it much) ....

http://hints.macworl...110606033134359

#19 Shadrack

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Posted 14 October 2012 - 16:23

UPDATE:

Okay this is incredibly interesting. I'm now 100% sure this is indeed a software issue, rather than a hardware related one. For whatever reason OS X Mountain Lion is telling my iMac to increase CPU fan speed in order to cool off. But apparently this is a one-way street. As time progresses the fan speed just continues to go up until it hits a maximum of about 4150 rpm. Like jamesyfx noticed they it will continue running at its maximum until I do a full shutdown. So for whatever reason OS X Mountain Lion won't tell my iMac to reduce fan speeds once it cooled off.

After a lot of Googling I noticed other people having the same issue with OS X Mountain Lion. Not just iMacs but MacBook Pros too. One person came with the suggestion to temporarily download and install iStat Menus 2, set Fan speed control to "Medium" (it's on of the default "rules") and then return to "Default". In literally an instant my iMac's CPU fan would drop from its maximum of ±4150 to a quiet 1940 and then continued to drop.

Check out the below screen shot and note the uptime: Over 6 hours and a regular CPU fan speed of 1885 (it's still dropping as I type).

So what's going on here people?


I'm confused. Did that software package end up solving the problem for you or is it still an issue?

#20 OP .Neo

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Posted 15 October 2012 - 07:42

I'm confused. Did that software package end up solving the problem for you or is it still an issue?

It solved the problem until the next restart.

#21 FightAndLive

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Posted 15 October 2012 - 07:48

Off hand I would say the temp gauges are wrong, without touching the cpu or the motherboard touch the bottom of the heat sink(while the computer is on) and see if its hot. That feels like the CPU is over heating(which would cause the 100% cpu usage).

#22 OP .Neo

.Neo

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  • Joined: 14-September 05
  • OS: OS X Yosemite
  • Phone: iPhone 5s

Posted 15 October 2012 - 09:54

Off hand I would say the temp gauges are wrong, without touching the cpu or the motherboard touch the bottom of the heat sink(while the computer is on) and see if its hot. That feels like the CPU is over heating(which would cause the 100% cpu usage).

I have no idea what you're talking about or why you think there is 100% CPU usage. :/

#23 iUserX

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Posted 24 October 2012 - 20:52

Buy a new iMac :p