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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 speed running at full speed


I have iMac 21,5'' from 2011 with SSD Drive and i have problem since yesterday.

What happened?

After boot (10 minutes, 15 minutes, sometimes only need to 1-2 minutes) CPU FAN turns on full RPM.

I checked temperatures in Macs Fan Control and they're all ok.

I did NVRAM and SMC reset, and nothing.

I have SSD drive, but i bought him without HDD.

Can you help me? I don't know what can i do.

I opened it but I do not see anything suspicious inside.

With CPU FAN 100%, iMac frees 50% :(

Since i opened it, fan rpm is in the norm.

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Have you installed a third party drive?


This is Patriot Blast 240GB, but i have this Mac since half year and problem with cpu fan is since yesterday.


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Hey Michal

If the you have successfully reset the NVRAM/PRAM and the SMC and the problem persists, this seems like a software issue. Check to see in Activity Monitor if there are any Processes or Programs running in the background that are using a lot of your memory and processors power.

Sometimes Mac's will increase the speed of their fan's depending on if the Mac needs to turn on Turbo Boost which is a feature all Intel-based Mac's have. This allows the Mac to use more CPU power like overclocking. Also, you can check your startup list in the "User and Accounts" pane in System Preferences to see if there are programs running on startup

Good Luck!

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Michał Paczyński will be eternally grateful.
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