GABLAD Posted January 18, 2015 Share Posted January 18, 2015 Hi there. 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...). Here's the problem: it takes about an hour for the CPU fan to gradually speed up from the initial approx 1200 RPM to around 4000 RPM (which is quite noisy). 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 control, 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 did, 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? Link to comment Share on other sites More sharing options...
nosense Posted January 18, 2015 Share Posted January 18, 2015 http://exirion.net/ssdfanctrl/ It allows me to control my fan speed on my MBP, not sure if it works on your imac. Link to comment Share on other sites More sharing options...
GABLAD Posted January 18, 2015 Author Share Posted January 18, 2015 http://exirion.net/ssdfanctrl/ It allows me to control my fan speed on my MBP, not sure if it works on your imac. This software is great but has no CPU fan control, only Hard Drive and Optical Drive fan control. The problem resides in the CPU fan. Link to comment Share on other sites More sharing options...
nosense Posted January 18, 2015 Share Posted January 18, 2015 This software is great but has no CPU fan control, only Hard Drive and Optical Drive fan control. The problem resides in the CPU fan. Have you tried it? It controls the main cpu fan for my MBP. Link to comment Share on other sites More sharing options...
farmeunit Posted January 18, 2015 Share Posted January 18, 2015 I've used this. NOT free, though. http://www.hddfancontrol.com/ It was after a drive swap, but as previous poster mentioned, worked on CPU. Link to comment Share on other sites More sharing options...
GABLAD Posted January 19, 2015 Author Share Posted January 19, 2015 Have you tried it? It controls the main cpu fan for my MBP. Yes i've tried it, but only HD and optical fan control appear on the main window... I've used this. NOT free, though. http://www.hddfancontrol.com/ It was after a drive swap, but as previous poster mentioned, worked on CPU. As I wrote in the initial explanation, I tried HDD Fan Control, SMCfanControl and iStat Menu fan rules too, but nothing comes out of any of them. Link to comment Share on other sites More sharing options...
Sikh Posted January 19, 2015 Share Posted January 19, 2015 This WILL control all of the available fans. Its also free http://www.macupdate.com/app/mac/23049/smcfancontrol Zoom7000 1 Share Link to comment Share on other sites More sharing options...
ATLien_0 Posted January 19, 2015 Share Posted January 19, 2015 How much ram do you have free in your activity monitor? I've noticed both on my macbook pro and office iMac that the fans go crazy when I start hitting my memory limits. Link to comment Share on other sites More sharing options...
Frankenberrie Posted January 19, 2015 Share Posted January 19, 2015 Check your heatsink. Make sure the clamp did not break or come loose. Ive seen this happen in PC's. Although the heatsink looks like its on correctly if a clamp broke or is loose the heatsink will not touch the CPU correctly. Hope this helps. Link to comment Share on other sites More sharing options...
GABLAD Posted January 19, 2015 Author Share Posted January 19, 2015 This WILL control all of the available fans. Its also free http://www.macupdate.com/app/mac/23049/smcfancontrol Here's the thing. I already tried SMCfanControl. But just to give it another go, I downloaded it again. Nothing changes. Anyway, doesn't it regulates the MINIMUM speed only? My problem resides in the maximum speed which is constantly and gradually rising, not the minimum speed. SMCfanControl has nothing for me, i fear. How much ram do you have free in your activity monitor? I've noticed both on my macbook pro and office iMac that the fans go crazy when I start hitting my memory limits. Computer is running at idle. No automatic background download or update (i disabled those). Plenty of RAM left from the 8 GB. Check your heatsink. Make sure the clamp did not break or come loose. Ive seen this happen in PC's. Although the heatsink looks like its on correctly if a clamp broke or is loose the heatsink will not touch the CPU correctly. Hope this helps. That's more the kind of answer I looking for! See, I fear it's something related to the hardware, which would be weird since I never opened the case... But since nothing else seams to work, this is maybe where my answer is... But just before I crack open my iMac, I'd like to see if anyone ever had the same issue. I've read about folks with similar fan problems, that occurred after a hard drive swap and a bad reconnection of the temperature sensors... Link to comment Share on other sites More sharing options...
GABLAD Posted January 19, 2015 Author Share Posted January 19, 2015 UPDATE: For some reason, the CPU fan sometimes stay put. Now it's been sitting aroudn 940 RPM (which is Apple's minimum speed limit) for an hour. I made a test to see if there was any sort of trigger that would send the fan on a crazy train... So I launched around 10 heavy applications (Photoshop, Lightroom, etc.) at the same time and it stayed there, right at 940 RPM. Now I turn on SMCfanControl and start playing with settings. I manage to bring the CPU fan and the 2 others (HD and optical) to all sort of speeds without any problem. So SMCfanCOntrol CAN control the fan, but there is still some sort of trigger that sends it up hill. Anyone has an idea what that trigger could be? Sense would be that it would be related to CPU usage... Link to comment Share on other sites More sharing options...
binaryzero Posted January 20, 2015 Share Posted January 20, 2015 lol, I wouldn't worry. Link to comment Share on other sites More sharing options...
Ph1b3r0pt1c Posted January 20, 2015 Share Posted January 20, 2015 You could have a sensor going bad. There is one on the hard disk, under the cpu, on the video card, and one on the superdrive. We used to have roughly one a week come to us doing this when I worked for simplymac. May want to take it to an auth retailer and have it looked at. Edit: Is this one of the 27in that had the hard disk replacement program? If it is I can almost guarantee its the sensor on the hard disk. Link to comment Share on other sites More sharing options...
macoman Posted January 20, 2015 Share Posted January 20, 2015 I could be wrong but have you tried to wipe the HDD and install a fresh copy of the latest OS X Yosemite? Also did you downloaded the latest firmware for your iMac? Link to comment Share on other sites More sharing options...
WinMacLin Guy Posted January 20, 2015 Share Posted January 20, 2015 None of these fan programs will help set a maximum speed, nor should they because increased heat and the inability for the fan to respond to it is not good for the computer components. I would say try running a few Flash videos on your mac and see if you encounter the increase (if you use youtube for this make sure that you are using the flash player not HTML5 and of course also make sure the plugin is running [as of Mavericks, the plugins do not start automatically on many websites]). I have noticed that both with my Mac and my friends' Macs that whenever you let Flash player run the fan speed would gradually increase until it is running at or close to its maximum speed. Link to comment Share on other sites More sharing options...
nosense Posted January 20, 2015 Share Posted January 20, 2015 I guess it doesn't work for Imac(ssdfancntrl), but it controlls my cpu fan speed on a MBP None of these fan programs will help set a maximum speed, nor should they because increased heat and the inability for the fan to respond to it is not good for the computer components. I would say try running a few Flash videos on your mac and see if you encounter the increase (if you use youtube for this make sure that you are using the flash player not HTML5 and of course also make sure the plugin is running [as of Mavericks, the plugins do not start automatically on many websites]). I have noticed that both with my Mac and my friends' Macs that whenever you let Flash player run the fan speed would gradually increase until it is running at or close to its maximum speed. Link to comment Share on other sites More sharing options...
(Account no longer active) Posted January 20, 2015 Share Posted January 20, 2015 Anyone has any idea? Anything I could try? I'd start with resetting the SMC and PRAM (presume you've done that already); this fixed a similar issue on a friend's mid-2011 27" iMac (from memory). http://thenextweb.com/lifehacks/2010/12/04/how-when-why-to-reset-the-pram-smc-on-your-mac/ Flash is a problem on Macs; try running with it disabled for about an hour and see if the fans still kick in. Link to comment Share on other sites More sharing options...
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