Fans going crazy, CPU 100% idle


Recommended Posts

I'm going insane over the behavior of my 27-inch, medio 2010 iMac. The CPU fan continues to spin up even though the iMac doesn't do a thing. I've reinstalled OS X Lion multiple times, I reinstalled OS X Mountain Lion several times. I did PRAM-resets more times I can count, same goes for SMC resets. Today I even disconnected the iMac, laid it down on my bed and cleared all the vents with the vacuum cleaner on the weakest setting. The other day a friend of mine walked in and immediately asked why my iMac was making so much noise.

The first picture shows the CPU Fan right after startup. The second less than two hours later. I haven't done a thing with the iMac except play music and browse the web a bit.

How on Earth is it possible the fans spin up, sometimes over 4000 rpm, when the CPU sits next to idle most of the time? The worst part is they won't power down once the iMac cooled off. There are no optical drives in the SuperDrive either.

The measurements are in Celsius. The room temperature averaging at 20,5 degrees throughout my apartment. It's only 14 degrees here in Amsterdam.

post-128385-0-15321200-1348764232_thumb.

post-128385-0-38335300-1348764664_thumb.

post-128385-0-02210400-1348765019.png

Link to comment
https://www.neowin.net/forum/topic/1108523-fans-going-crazy-cpu-100-idle/
Share on other sites

assuming your temps are in Celsius it is spinning up because the chip is hot. Is there anything to justify the chip being hot? Dust on the HSF, high ambient temp, etc?

I can't really say for sure how much dust has accumulated inside the iMac itself, but judging by how little there was directly underneath the grill I seriously doubt it's a lot. I tried looking inside with a flashlight but everything seemed clear.

If I leave my iMac on for long periods of time the fans will gradually get faster and faster until they are 100% on, and they will not go back to normal speeds unless I shut down and power back on. Rebooting just keeps them running at full tilt.

It's strange. It's like the driver/sensor controlling it has failed to do it's job properly. :/

Yeah if it's THAT hot at idle, you have a problem on your hands.... either your system has absolutely 0 airflow or the heatsink aint applied correctly, if so I'd take the computer and bring it to a store.

Did you recently install an SSD?

http://forums.macrum...d.php?t=1235234

That actually affects the hard drive fan, not the CPU fan (at least it did in my Late 2010 iMac). Also, it happens a lot sooner than 2 hours after boot. :p

Maybe your GPU is being taxed by something? The CPU fan cools both, so...

Yeah if it's THAT hot at idle, you have a problem on your hands.... either your system has absolutely 0 airflow or the heatsink aint applied correctly, if so I'd take the computer and bring it to a store.

It's an iMac. It's normal for things to run a little bit hotter.

Did you recently install an SSD?

Everything is stock. No modifications whatsoever have been made to the iMac after I unpacked it. Also, the SSD issue wouldn't affect the CPU fan, rather the HDD fan.

Maybe your GPU is being taxed by something? The CPU fan cools both, so...

Okay, this is something I can work with. Is there any way of checking what the GPU load is?

If I leave my iMac on for long periods of time the fans will gradually get faster and faster until they are 100% on, and they will not go back to normal speeds unless I shut down and power back on. Rebooting just keeps them running at full tilt.

It's strange. It's like the driver/sensor controlling it has failed to do it's job properly. :/

That's EXACTLY what ****es me off. The fans won't slow down once things are cooling off.

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?

post-128385-0-90926700-1348790216_thumb.

It does a similar thing on my system, CPU fan speed drops down to a steady 1190rpm when I set to default.

Seems like it kicks the default behaviour back in once you set it as such.

My iMac is a completely different model to yours, so the issue must be software related.. and I think using this utility has proven that.

Yeah that's exactly what seems to happen. iStat basically slaps OS X on the wrist telling it do proper fan control. After a while CPU fans would indeed drop to an average of 1190 rpm on my model as well. Here I was thinking my CPU/GPU fan was constantly triggered because it couldn't handle the new OS X Lion/Mountain Lion graphics effects. But that's not it either.

Anyway, it seems like you can uninstall iStats Menu from your system until you do a SMC reset.

I'm not familiar with Mac since i never owned one but why does OSX has to control the fan ?

I would never ever trust any OS to control the fan speed of my computer. Right now i have a fan controller but if i would not have one i would let my Motherboard control the fan speed or at worst install my MB software (or a 3rd party alternative like speedfan) to control them.

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.

  • 2 weeks later...

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

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?

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. :/

  • 2 weeks later...
  • 2 years later...

Hi there, old thread, but hopefully someone is still around.

I have an iMac 27 late-2009, 3.06 Ghz, 8gb RAM, running OS 10.8.5, and all the hardware is original (no HD swap...). So, it has a similar problem: it takes about an hour for the CPU fan to gradually speed up from the initial approx 1200 RPM to around 4000 RPM. Then, all I have to do is to put it to sleep for enough time to let the fans stop spinning (that's not even 5 seconds) and then wake it up to see the CPU fan at normal speeds. And here it goes for another hour of gradual increase... See the screenshot of the iStats Menu, the graph shows the increase in the last hour, and the three previous increase/sleep patterns... The other two fans are just fine. All of that time, the iMac is at idle, nothing running at all. My iMac isn't my main computer, so i kinda left the problem as it was, spending an hour or so every couple of months trying to solve the issue, but after these 5 years of fruitless efforts, I can't believe I haven't solve it yet! Even though I get answers a lot from forums, here's my first post in one of them (ever!), in hope it will help.

 

Here are the solutions I tried already: smcFanControl, HDD Fan Control, iStats Fan Rules... Nothing seems to be able to override the fan speeds, nothing at all! I vacuumed the air input and output... And of course, I did the SMC reset. I try to remember all the other things I tried to do, but it gets confusing after those years of diverse problem solving. I did many upgrades (and even downgrades) too but I doubt it has anything to do.

 

Even though I never opened the iMac's case (I DID open the bottom latch to replace RAM memory at some point, comes to my mind... but that's not the back case) I wonder if it has anything to do with some hardware that would just be misplaced at the factory of because of a shock while moving the computer around... 

 

Anyone has any idea? Anything I could try?

 

Screenshot:

https://www.dropbox.com/s/vfvkr1zordrbznb/Screen%20Shot%202015-01-14%20at%2011.59.57%20PM.png?dl=0

This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Posts

    • Nudge me when they bring back hardware audio acceleration so I can get my EAX 5 back. We've evolved graphics to real-time path tracing, but regressed audio some 15 years back in time with this stupid software audio stack.
    • Ocenaudio 3.19.4 by Razvan Serea  Ocenaudio is a full featured, fast and easy to use audio and music editor. It is the ideal software for people who need to edit and analyze audio files without complications. Ocenaudio also has powerful features that will please more advanced users. To assist ocenaudio development, a powerful toolset of audio editing, analysis and manipulation called Ocen Framework was created. ocenaudio is also based on Qt framework, a well known library for cross-platform development. Cross-platform support ocenaudio is available for all major operating systems: Microsoft Windows, Mac OS X and Linux. Native applications are generated for each platform from a common source, in order to achieve excelent performance and seamless integration with the operating system. All versions of ocenaudio have a uniform set of features and the same graphical interface, so the skills you learn in one platform can be used in the others. VST plugins support Ocenaudio supports VST (Virtual Studio Technology) plugins, giving its users access to numerous effects. Like the native effects, VST effects can use real-time preview to aide configuration. Real-time preview of effects Applying effects such as EQ, gain and filtering is an important part of audio editing. However, it is very tricky to get the desired result by adjusting the controls configuration alone: you must listen the processed audio. To ease the configuration of audio effects, ocenaudio has a real time preview feature: you hear the processed signal while adjusting the controls. The effect configuration window also includes a miniature view of the selected audio signal. You can navigate on this miniature view in the same way as you do on the main interface, selecting parts that interest you and listening to the effect result in real time. Multiselection for delicate editions To speed up complex audio files editing, ocenaudio includes multi-selection. With this amazing tool, you can simultaneously select different portions of an audio file and listen, edit or even apply an effect to them. For example, if you want to normalize only the excerpts of an interview where the interviewee is talking, just select them and apply the effect. Eficient edition of large files With ocenaudio, there is no limit to the length or the quantity of the audio files you can edit. Using an advanced memory management system, the application keeps your files open without wasting any of your computer's memory. Even in files several hours long, common editing operations such as copy, cut or paste happen almost instantly. Fully featured spectrogram Besides offering an incredible waveform view of your audio files, ocenaudio has a powerful and complete spectrogram view. In this view, you can analyze the spectral content of your audio signal with maximum clarity. Advanced users will be surprised to find that the spectrogram settings are applied in real time. The display is updated immediately when altering features such as the number of frequency bands, window type and size and dynamic range of the display. Ocenaudio 3.19.4 changelog: Adds fallback fonts so every language and symbol displays correctly Improves autosave and session recovery stability Improves region navigation and display Fixes a crash when the level meter is used on displays with a scaling greater than 200% Fixes memory corruption when using the silence selection tools Fixes crashes when closing a file while effects are still being processed Fixes a freeze when applying effects to many files at once (macOS) Fixes crashes related to audio devices on Windows Fixes invalid file names when exporting regions whose label is used as the file name Other bug fixes and improvements Download: Ocenaudio 64-bit | Portable | ~40.0 MB (Freeware) Download: Ocenaudio for Linux and Mac OS View: Ocenaudio Homepage | Screenshot Get alerted to all of our Software updates on Twitter at @NeowinSoftware
    • Hasleo Disk Clone 5.8.2.1 by Razvan Serea Hasleo Disk Clone is a free and all-in-one disk cloning software for Windows 11/10/8/7/Vista and Windows Server that can help you migrate Windows OS to another disk, clone one disk to another disk or clone one partition to another location quickly and efficiently. Completely Free Windows Migration and Disk/Partition Cloning Software Migrate Windows from one disk to another without reinstalling Windows, apps. Clone one disk to another and makes the data on 2 disks are exactly the same. Clone a partition to another location without losing any data. Easily adjust the size and location of the destination partition. Convert MBR to GPT or convert GPT to MBR by cloning. Creation of Windows PE emergency disk. Extremely fast cloning speed and multi-language support. Supported OS: Windows Vista/Server 2008 or later, fully compatible with GPT and UEFI. Hasleo Disk Clone 5.8.2.1 changelog: Fixed an issue that caused disk enumeration to fail Fixed an issue where WinPE created under Windows ARM64 26H1 did not work properly Download: Hasleo Disk Clone 5.8.2.1 | 32.3 MB (Freeware) Link: Hasleo Disk Clone Home Page | Screenshot Get alerted to all of our Software updates on Twitter at @NeowinSoftware
    • This got me thinking, would you rather a self driving car prioritise protecting its passengers or everyone else? I'd choose the one that keeps me and my kids safest. At some point, these cars have to make those choices already, don't they? Wonder if we have a way to find out what way they lean.
    • The proportion (or number of iterations) has nothing to with this aspect of Copyright I am describing. In short, it doesn't matter how many times the manager tells you to change something or how. Your work product is always YOURS until and unless you then assign that to the person representing the client/company, usually for financial compensation -- either in salary or as a subcontract work for hire payment. if iterations determined copyright, then businesses would have learned to just keep making changes until they could claim they owned the copyright, without having to compensate the artist for their work. And that would be BAD. The only place where the amount of changes does have a role is in how much does a human modify a previous public domain work (from any source) before it is considered fair use or their own work, etc. For example, if a human makes substantial changes to a public domain (re: AI, by definition) work, then they can then claim that derivative work as their own...but NEVER the original version, of course. That's why anyone can make a movie about Dracula, for example, as long as it is based on the public domain novel, but not if they take new ideas from copyrighted movies made afterwards. As one of the people who personally advised the US Copyright Office on their recent ruling on these very issues, be assured that I specifically used the terminology precisely -- though I made it simple enough for laymen to understand it. If I made this confusing by doing so, I apologize. But, to be clear regarding your assumption that I would agree to your second statement that I quoted above -- the answer is NO. If AI does the work, no matter how much "direction" you give it, it cannot be copyrighted. All AI generated content is in the Public Domain and therefore the copyright cannot be assigned to ANYONE, even you -- until and unless substantial modifications are made to it BY A HUMAN BEING (yourself or a contracted artist/writer/etc.) and then that copyright on the derivative work is legally (in writing) transferred to you. This is a critical distinction. And it is important that people, especially AI sloppers, understand this. For example, YouTube is not paying AI slop generators for the copyright, etc. of their AI slop. What YouTube is doing is sharing AD REVENUE for permission to publish your AI slop. Copyright/ownership/rights never come into it. Importantly, that means that anyone can copy any AI slopware on YouTube, etc. and rehost it anywhere they want, even back on YouTube, and there is nothing legal that YouTube can do about it with regards to copyright protections, ownership, DMCA, etc. Anyone is legally free to use any AI slopware in any way they want. When this ruling was pending, I warned Disney legal of all of this before they did their OpenAI deal -- that it would literally dilute their entire IP portfolio forever. They ignored that warning for the PR and stock bump. But that is why, when the ruling came down last year, Disney quickly extricated themselves from that OpenAI deal, even eating the initial upfront fees -- followed closely by OpenAI ending their entire AI video generating business model. They adjusted their PR release dates to make this less obvious to shareholders, of course. Phew. I hope that this clears up the key distinctions for you and anyone reading. If you have any additional questions or even hypotheticals about AI and Copyright, please feel free to ask.
  • Recent Achievements

    • Collaborator
      ryansurfer98 went up a rank
      Collaborator
    • Week One Done
      Eurosoft10 earned a badge
      Week One Done
    • One Month Later
      Eurosoft10 earned a badge
      One Month Later
    • One Year In
      Skeet Campbell earned a badge
      One Year In
    • One Month Later
      Sharbel earned a badge
      One Month Later
  • Popular Contributors

    1. 1
      +primortal
      553
    2. 2
      +Edouard
      188
    3. 3
      Michael Scrip
      78
    4. 4
      PsYcHoKiLLa
      74
    5. 5
      neufuse
      71
  • Tell a friend

    Love Neowin? Tell a friend!