Blizzard games are extremely graphics and processor intensive. When I play WoW, my computer ramps up to 75 degrees Celsius in a matter of minutes, topping off at around 80. You might want to check for dust, as I checked the blizzard forums, and several threads suggested that the computer's insides got dusty from constant fan use (because of the high temps.) They had the same beeping problem, and most were fixed by getting the dust out.