If you´ve got a modern CPU, you need a CPU cooler.

Gone are the days when PC CPUs could get away with just a little aluminium heat sink stuck on top of them, or no cooler at all. When any Intel or AMD CPU on the shelves today is going full blast, it´s pumping out heat - less than 20 watts for current Celerons, less than 30 for current P-IIIs, something around the 40 watt mark for current Durons, and better than 70 watts for top-of-the-line Athlons.