Nowadays every PC that come of the market are hot.. not hot in good way, but hot that is hot enough to fry an egg. Without proper cooling your PC can produce heat up to 350 C, as hot as an oven.Now to PC user this may seem fine, but in the hands of modders and over clockers that squeeze every ounce of performance power out of their PCs this may cause a problem as you modify your PCs factory setting you tend to increase it’s power output thus generating more heat. The traditional heatsink is will do for most PC users, but for serious PC afficionados this will never do, so they use cooling fans, and a much more tricky approach which is water-cooling.
Heatsinks - these are chunks of high thermal conducting metal such as aluminum, copper, etc. As electric warms up the components it dissipates through the heatsink, that’s why heatsinks are more like fins as the heat spreads over the surface it dissipates through the fins which are surrounded by cooler air.
Cooling Fans – these work like heatsinks but well they use fans to suck out the hot air and blow cooler air. Now the more cooling fans you add to your rig the more cooler it gets, but the more fans you add the noisier your Rig gets, so over clockers look for other cooling solution such as Liquid Cooling.
Liquid Cooling – the best but hardest way to cool your PC, a liquid cooled PC moves fluid over hot components transferring the heat from those components to the liquid, then the hot liquid goes to its cooling block the cycle back again, a liquid cooled PC maybe the best solution but also think of the maintenance and the cost of leaked, or clogged tube which could damage the PC electrical component in an instant. Now there are liquid coolants out in the market that works better in cooling your PC such as distilled water and add them up with anti-corrosion liquids and non-toxic fluid additives to care for the environment, yourself and your PC. Maintenance of these liquid cooling system must be checked at least once a month, and the liquid coolant itself must be change annually to prevent algae buildup in your cooling tubes.
via [PCExtreme]
It has happened with Vista and is seemingly also being built into 
