How to prevent Blender to overheat my computer while rendering? How do I prevent Blender to overheat my computer while i'm rendering I hight resolution image? 

I use a MacBook Air OS X Yosemite

Proccesor: 1,4 GHz Intel Core i5
Memory: 4 GB 1600 MHz DDR3
For complex rendering in general, reducing the "threads" can help. (Under performance tab in render)
The computer will auto-calculate it, but you can set it lower than the auto value through the "fixed" option. The render will be slower, but it will be less intense and cause less heating/crashes.