More on Good Heatsinks

Air circulation on the heatsink

Believe it or not, there can be good and bad air circulation on the heatsink. Well designed heatsinks promote air travel between the fins, which in turn promotes heat transfer from the fin to the surrounding current of air. Without a flow of air, a heatsink fin holding heat is useless. The popular design nowadays is the crosscut fin style, which allows air to travel in both directions along the heatsink. This design works out well, and with the advent of heatsinks that have 2 fans attached, can move a lot of air through the fins.

What's it made of?

The majority of heatsinks are produced of aluminum. The main reasons are that aluminum is cheap, easy to work with, and heat travels through it well. Although there are other materials that would prove better, they are either too hard to work with (copper) or are prohibitively expensive (silver). Ideally, a silver heatsink would be the best in terms of heat transmission, but how much would that cost? For now, we'll stick with aluminum due to its price and ease of manipulation. Also, it's been noted that the process of anodizing aluminum actually helps out with its heat transfer abilities. So, feel free to pick up those bright blue, gold, black, and other weirdly colored heatsinks without I-Mac shame. Take a look at Tennmax's shiny, anodized aluminum heatsink, shown below:

Measuring up a heatsink

The most common form of measurement that is used to determine the effectiveness of a heatsink is its thermal resistance. Thermal resistance measures the ability of the heatsink to absorb heat away from another object, like a CPU. The units are given in degrees Celsius / watts. If a heatsink had a thermal resistance of 1, for example, then every watt the CPU uses will cause it to rise 1 degree Celsius. Thus, a lower thermal resistance number is better. A good PII/PIII heatsink is somewhere in the range of .7 - 1, whereas socketed CPUs' heatsinks perform a bit better, having numbers around .5 - .7.