The purpose of this article is to take a very fast, very hot modern processor (in this case an AMD Athlon 64 4000+) and underclock it with an eye to comparing performance to levels of heat and voltage at below stock speeds. The Athlon 64 is currently the fastest available desktop processor, so we reasoned that reducing its speed to the point where it could be operated silently with a passive cooling system should still leave us with a powerful machine for everyday tasks.