You can do a few things that check the temperatures and warn you if it reaches a critical degree. Speedfan is one of that programs that does exactly this. It checks all temperature sensors, most important are the cpu temperature and the hard drive temperature. The tool is also able to manage all fans of your computer, it can throttle them to make them less noisy or speed them up to cool the air in a better way.

The motherboards will have to support this functionality of course, most modern ones should. Lets say all fans are working 100% and your components are still getting to hot. You could start by checking the airflow in your case. Where is the fresh cool air coming in, where is the warm air going out. Are all components in the flow or is it missing some ?

If you are using a standard cpu cooler you should think about adding a more powerful cooler to your system. Regular coolers are great for normal use and temperatures that stay in their limits but fail when some variables change to the extreme.

Another easy trick would be to take a normal fan, open your case and direct that normal fan towards your case. This should cool everything sufficiently. An open case leads to more dust inside the computer, make sure you clean the dust regulary.

You could also check the fans and clean them. Especially useful if you are a smoker.

Cables tend to block the airflow, use cable ties to tie them together and put them out of the way of the flow.

Do you have additional tips that keep your computer from overheating ? Let me know.