Did you notice your MacBook Pro fan is getting louder? This means that your Mac is overheating. This can be caused by applications that use up a lot of your computer's resource or is simply the result of having your Mac on for too much time and or thermal compound between the heat sink and CPU, GPU have stopped cooling.
Download & install "smcFanControl" lets you monitor the current temperature (in Celsius or Fahrenheit), assign different minimum speeds for each fan using sliders, and even apply different settings when your power source changes.
It can do more than just display your Mac's internal temperatures - It can actually control the fan speed of your MacBook. Apple Mac OSX is programed to keep the fan as low as possible to minimize the noise level. When CPU temperature exceeded 100C (195-215F); and even then, only barely increase fan speed to keep it below 100C (215F). Not cool enough to cool down your computer; can cause damages to your Mac's logic board.
To adjust the speed of your Mac's fans go to temperature reading on the menu bar and choose the preferences option from the drop-down menu. From there simply move the slider to the desired fan speed (there may be more than one slider if your Mac has more than one fan) and click the save button. Note that the minimum fan speed that SMC Fan Control allows you to select is the normal, default fan setting - Sliding the slider higher will simply set a higher minimum fan speed.
When you have set minimum fan speed to Max (6000rpm), and your Macbook Pro temperature still doesn't stay below 80C (176F); your Mac is overheating due to the Cooling System internally. Take it to your local macbook pro repair shop for a service.
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