I hear about all these people killing their computers! What gives? I have never had a problem. I did a volumetric world render of one of my posts and that thing ran for a week solid and then I got tired of waiting. I didn't know you could run multiple instances. I just modelled some things in wings to pass the time. I hardly ever hear my fan kick into the highest speed. Most of the time in a long render the air coming out is just a little warm. Maybe it's the cooling system. If you look into the back of mine you can see a half-inch tall 3-inch wide copper wire network. I'm not sure if the air gets sucked in there but it can get a tad warm.