해결 되 었 습니다 : Why is the fan so loud ? - iMac Intel 27 " EMC 2429 - iFixit 
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 Why is the fan so loud ? 
 The fan on my iMac Intel 27 " is so loud and I wonder how to fix it 
 Do you have any other symptoms other than a loud fan ? What are the last three numbers of your serial number ? 
 rj 713 의 답변 2011 년 11 월 30 일 
 is it just loud or is it screeching ? 
 mayer 의 답변 2011 년 12 월 01 일 
 Maybe the fan is heavier because of the dust on it 
 zionthelion 73 의 답변 2012 년 01 월 18 일 
 My 27 " imac had the same problem . The problem was the Ambient Temperature sensor . The ambient sensor plug is on other side of CPU processor . And I think about the temperature of processor , it caused desoldering of logic board one of the capacitor of temperature sensor system . Sorry about my english , It was my problem and was solved , maybe could help others ! 
 gilmilbratz 의 답변 2014 년 11 월 19 일 
 The problem here is that the OP never came back and told us her exact machine so all the answers are just speculation . 
 mayer 의 답변 2015 년 01 월 09 일 
 평점 : 11 . 2000 
 I wouldn ' t just drop lubricant on the fan . If the fan is clogged with dust or nicotine it will slow it down even more . 
 If you can access the fan use some 91 % ( or 91 - 99 %, do not use anything with a lesser percentage as they can be conductive and if accidently dropped onto a system / logic board can cause electronic components to short out ) Isopropral ( rubbing / the white NOT green stuff ) alcohol and a brush to clean away the dust and debris then add about 2 drops of 3 and one oil down in the center where it gets inside of the fan housing . 
 If it still makes noise , you probably have a bearing going out - these fans spin hundreds of revolutions per second and will simply wear out . .. in this case , replace it , the fans only cost a few bucks . 
 When your in there also use something like a tooth brush , with a dab of alcohol ^ mentioned above to clean off any dust on the exhaust vents . 
 Country Computer Service 의 답변 2012 년 01 월 18 일 
 평점 : 626 . 9000 
 If you changed the hard drive to one without Apples firmware , this can cause run away fan issues . 
 Then how can we solve the problem ? 
 dkhyun 의 답변 2012 년 12 월 16 일 
 jcarter - Which system do you have a ' 09 or ' 11 model ? There are different answers here depending on the system . The ' 11 cable is the link from OWC below in my answer . 
 Dan 의 답변 2015 년 01 월 10 일 
 11 / 30 / 17 - Just to update this old question , 
 I installed a 3 . 5 " Seagate FireCuda SSHD into a 2011 27 " with no temperature cable . Got the expected racing fan issue , installed the OWC 2011 Thermal sensor adapter and issue is gone ! 
 OWC - In - line Digital Thermal Sensor for iMac 2011 
 mayer 의 답변 2017 년 11 월 30 일 
 평점 : 336 . 4000 
 게시 됨 : 2014 년 09 월 18 일 
 westly 197 - Well , Yes & No here . .. 
 From the ' 11 model forward Apple uses custom firmware within the HD to allow the internal thermal sensor ( note : not all drives have this sensor ) to be used as part of its SMC services which in turn controls the RPM ' s of the fan or fans of the system . If you try using an older non - compliant drive the fans will ramp up as SMC services will think the sensor within the HD is defective . Over time the fans will wear out and the system will be very noisy compared to what it should sound like . Heres a collection of good write - ups from OWC that describes the issue : Apple Further Restricts Upgrade Options on New iMacs and Apple ’ s iMac 2011 Model Hard Drive ‘ Restrictions ’ and iMac Hard Drive Upgradeability Expanded ! 
 OWC created a special cable so people could put in noncompliant HD ' s into the ' 11 system ' 11 Upgrade kit at the same time Apple was also working with the JEDEC standards group which over see ' s the SMART HD standard . While it took quite a bit of time Apple was able to get the group to alter the standard so the thermal sensor with in the HD could be accessed in a common method and not interfere with the performance the the drive ( which was why Apple needed to go with custom firmware at the beginning ) . Now HD ' s that comply with the updated standard no longer need the OWC cable and have the newer SMART services within their firmware . 
 If you look at the HD ' s package you should see an Apple logo on it which is the only clue that I know of . The reason you don ' t see anything other than that is the drive vendors still have a lot of noncompliant drives out there and they have also being going though a bit of a market collapse and contraction ( being more focused on survival ) . I also suspect Apple may also be asking for a bit of money for the drives they certify as workable . 
 In the end you need to be smart shopper on what you buy . 
 Hey Dan , I have the 2011 iMac and just faced this issue so thats why its on my mind . Also the newest models are less likely to have fan issues . I am interested in knowing what drives might work without the need for the cable . I ' ve not heard this before and was under the impression only an Apple drive with special firmware for the mid 2011 models was required . Ive not read anything indicating any off the shelf standard drive would work . 
 westly 197 의 답변 2014 년 09 월 16 일 
 Svante Wahlqvist 
 Check if there are layers of dust on the blades or in the housing of the fans . Buy a can of pressured air and blow off the grit . Be careful to hold fragile components in place so they dont break , e . g . fan blades . 
 게시 됨 : 2012 년 11 월 29 일 
 there is no temp sensor cable on 2011 27 " iMac hard drive and I ' ve replaced it with the 1 TB WD from my 2010 iMac and I ' m sure that its the cpu fan not the hard drive fan that runs at full speed , I ' ve installed windows 8 using bootcamp and when I run fan control software in windows it shows that the GPU temperature goes to 69 to 74 degrees I think that might be the problem 
 if you hold alt option key and keep viewing the boot screen even for a long time the fan works just normal but when it starts to boot to an OS ( windows or OSX ) it starts to work at full speed 
 You are correct there is no external sensor like the older 2008 / 2009 had . The 2010 models used a special cable to gain access to the manufactures testing sensor . In the 2011 Apple was able to alter the drives they bought to have the sensor directly accessed though an unused pair of wires in the SATA cable harness . So both the 2010 & 2011 use the internal sensor for SMC to gain access to the heat levels of the drive to be more effective in system cooling . If the sensor cable ( 2010 ) or non - Apple HD in the 2011 model is not used SMC goes into fail safe ramping up the fans to offset the possibility of over heating . 
 Dan 의 답변 2017 년 11 월 29 일 
 In the iMacs I have worked on there is a temp sensor cable that runs from the hard drive to the logicboard . You are right that the hard drive itself does not have a fan but if the iMacs use a specific kind of hard drive and there is a thin cable that runs from the hard drive to the logicboard that is called a hard drive temp sensor cable . If that cable is missing it will cause the fan to run at high speeds . I learned about this while working at an apple store . Look it up . 
 The 2010 and there 2011 models now use the built - in sensor either via a custom cable per the given drive or in the case of the 2011 models Apples custom HDD ' s . 
 I had the same problem when I swapped out the HD in my imac 27 " mid - 2011 with an SSD drive . I believe the fan began running full throttle because it did not know how to process the temperature readings of the new drive etc . 
 I searched online and came across this website - http : / / www . hddfancontrol . com 
 ( Parenthetically - I am not that tech savvy but I do not recall seeing or detaching a temp sensor or wire ) 
 I installed their program and have not had any problems since ( it ' s been at least 6 months ) . 
 Using the hardware method is much better ! Here ' s what you need : OWC In - line Digital Thermal Sensor for iMac 2011 Hard Drive Upgrade . We have found the software methods are not as good and if the settings mis set can either wear out the fan ' s or damage the logic board . 
 That is true . The software from the website above is fantastic . About $ 35 . The iMac went completely quiet . You can set the temperature and speed of the fan as well . I strongly recommend it . Tin 
 Tin Aung 의 답변 2013 년 02 월 12 일 
 After installing 2 TB toshiba drive i got same problem . I solved it with ' Macs Fan Control '. No need to waste 35 $. Get fun 
 official link : http : / / www . crystalidea . com / macs - fan - cont . .. 
 Mitay 의 답변 2013 년 08 월 11 일 
 All I can say here is : Caveat Emptor 
 Any software solution that defeats the thermal controls the system has can effect your lifespan of your system or cause other odd effects . 
 The best approach on these systems is to use drives who ' s firmware works with the internal sensor correctly ( an OEM Apple drive ) or use a external sensor that intercepts the signal which is the solution I prefer so I can use any drive OWC In - line Digital Thermal Sensor for iMac 2011 Hard Drive Upgrade 
 Dan 의 답변 2013 년 08 월 11 일 
 There is a cable coming from the motherboard to the back of the screen that splits in two to the left of the ribbon cable , I guess the ambiance thermal monitor is there , it is cover with some tape , if the top plug unplugs the fan goes full speed it is very easy to do by tilting the screen , and not notice it , remove the tape very careful end re - plug the top plug and problem is solved . 
 Thats the older 2008 / 2009 models . The 2010 & 2011 use the internal sensor . 
 게시 됨 : 2014 년 12 월 29 일 
 Thank you Dan . I was going to purchase Apple brand harddrive used in 2013 Imacs . And then , I was going to install this hard drive in my 2011 Imac as a remedy . The harddrive you suggest , does it have to be a SSHD ? Can I use regular SATA 3 harddrive , as well ? 
 You ' ll need this special cable : OWC In - line Digital Thermal Sensor for iMac 2011 Hard Drive Upgrade 
 William Ferguson @ wmferguson 
 I have this issue on my 27 inch 2011 iMac . First showed up after a trip overseas and it was well packed in an airport " rock band " style case . Apple store in Spain could not resolve it . 
 Did you replace the hard drive at some point ? Fan ' s also do wearout . You might want to get a good thermal / fan sensor app like TG Pro it will allow you to see whats going on and let you test your fans . 
 Pol Obresleann 
 Reset SMC . Worked for me on iMac 2010 . https : / / support . apple . com / en - gb / HT 201295 
 I ' ve seen this problem before and it was because the hard drive was replaced with a different brand but the hard drive sensor cable was not changed . Different brands use different temp sensor cables . That might be the problem . 
 This model iMac doesn ' t have the sensor cable , there is no real work around aside from running software to control the fans ' speed . 
 maccentric 의 답변 2014 년 01 월 23 일 
 Botch job Ray @ suitslayer 
 게시 됨 : 2011 년 12 월 01 일 
 give it a good oiling with some grease . . don ' t use WD 40 it good but lasts only a few days . . give it a good clean as well . 
 Lube is the worse thing here ! It will act like a magnet collecting dust jamming up the fan . 
 Jessica Holst 가 / 이 대단히 고마워 할 것 입니다 . 
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