One of the biggest culprits for heat and consequentially noise in a PC is the video card. With graphics cards getting hotter and hotter, video card manufacturers have issues keeping many graphics cards running cool, as well as quiet. The standard method for cooling a video card is to use a small heat-sink, with a very fast fan attached to cool the video card. The main reason manufacturers do this is to save money as large heat-sinks cost more than a cheap fan that is cranked up.
However, many manufacturers offer special versions of their cards that have extra large heat-sinks, and are able to run cool with no fans at all! We have hand selected a few of our current favorite fanless graphics cards in our Quiet Video Card section.