The heat that you are concerned about comes from the processor and GPU, not the motherboard itself.
Different processors and GPUs produce different amounts of heat. For the GPU there is there is already a cooler installed so you don't have to worry too much about that. As for the processor, using the stock AMD cooler is fine but doesn't do very well when you overclock. Aftermarket coolers will make it cooler.
Beyond that, air flow in the case is also important.