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Model A1311 / Mid 2011 / 2.5 & 2.7 GHz Core i5 or 2.8 GHz Core i7 Processor

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Cpu fan running at full speed

I have replaced my HDD with a Crucial M500 480gb SDD. Now when computer boots up CPU fan runs at full speed all the time. I have tried HDD fan control but still can't get the fan to slow down. Tried it again with original HDD installed and fan was normal.

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Sorry I missed seeing this question when it was posted. Apple used proprietary heat sensor hard drives on this model. Changing the hard drive will cause run away fan issues. To rectify this use the OWC thermal sensor listed here:

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Thank you sir! I tried a software fan control with no help. I will order this and try next. Thank you again!


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Have you checked your serial number on this site:

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Thanks Cammy Unfortunately my Mac came with a 500GB Seagate HDD that was not eligible. After a little searching i found SMC fan control a free download. After installing i was able to control my fan speeds and set custom speeds for all 3 fans. My IMac is Happy again and faster than new.


I have this same issue. Since there was no fan for the HDD like the sata drive I wondered if that was the problem to cause the CPU fan to run like crazy. I will try the SMC fan control as well. Can anyone point me to what is normal fan speed or did you just set to minimum? This is a secretary's computer and she is techie so I can give her a number to watch for if we need to change the speed. I want her to notice if it gets above a certain temperature to change it, but I am not sure what to tell her to look for. Any recommendations?


Leave it on "Auto" and it should self-regulate.


Thank you Eric!


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rockcrusher40 will be eternally grateful.
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