Originally Posted by Freebase Dali

Well, I don't have much Mac experience, but overheating is overheating, regardless of the brand.
In most cases, your computer will have a mechanism to shut itself off immediately if it overheats to the point of near damaging.
But if you're simply just hearing a loud fan kick in, then your fan is just loud, and it's kicking in like normal fans kick in when the computer's temperature rises beyond a specific level.
But if your fan sounds like it's abnormally loud, and you're hearing some obvious signs of wrongness, you may just have to change out your fan.
Usually that's a better step to try first, as it's cheaper than just assuming your computer is overheating and buying something more expensive for it.

There are also free programs available on the web that can monitor and tell you what temperature your main hardware is running at.
You can then compare your readings to the average safe temperatures that you'll undoubtedly also be able to find on the web.


Either way, one obvious rule I like to observe, that I always see people ignore, is:
Never put your laptop directly on your bed or any like-surface. The venting underneath the laptop won't function and eventually your hardware will suffer over time. I see this all the time, and no matter how often I warn, people don't take it to heart. These are, 90 percent of the time, the same people who come to me later and complain about overheating issues. And usually by then, it's far too late.