Ultimately, you shouldn’t need to worry about cooling your Mac manually (though there are things you can do to help). Generally speaking, around 90ºc (194✯) isn’t unusual for a Mac under heavy load, but you want to keep things below 95ºc (203✯). You can also use a small app like smcFanControl to place a widget in your menu bar that displays how hot your Mac is running inside the case. Loud rattling noises are also a red flag and usually occur when bearings in the cooling mechanism work their way loose. What isn’t normal is a hot silent Mac, which could suggest that fans have failed. Remember that heat is a normal part of your Mac’s operation, and loud whirring fans means the machine is operating as normal in an attempt to cool itself down.
The computer should never be too hot to touch, though certain processes may make it uncomfortably warm, particularly if it’s a laptop that you are using on your lap. Under extreme load, it’s not unusual for your Mac to sound like it is about to take off. This means you will hear considerable fan noise when your machine is under load. While your Mac is hot, you should expect the fans to attempt to cool it down. The most obvious is that the Mac feels hot to the touch, particularly on the underside of the chassis if you have a MacBook. There are several tell-tale signs that your Mac is running unusually hot.
