NWA-PCUG Newsletter Article, June 2011
PC Cooling - Keep it Cool!
By Phil Sorrentino, President,
Sarasota Personal Computer Users Group, Inc., FL
February 2011 issue, Sarasota PC Monitor
president (at) spcug.org (click to email author)

Just like your car, your computer has to be cooled because it generates a lot of heat. Some of the computer’s components produce large amounts of heat during operation, and this heat must be removed in order to keep these components within their safe operating temperatures. PC Cooling, then, is the process of removing the heat from the computer’s components. Components which produce heat and are susceptible to performance loss and/or damage due to that heat include integrated circuits, such as the Central Processing Unit (CPU), graphics processors, chipsets, and memory. Hard drives also produce heat but typical air flow is usually adequate to keep them within their operating temperature. (Although some of the very fast drives (10,000 rpm), may need additional cooling.)

Most of the heat produced in a computer is generated by the power supply, the CPU and possibly the graphics processor. That’s probably where you’ll find the additional fans (beyond the normal chassis cooling fans). You might not think such a small electronic chip, the CPU, could generate so much heat, but many modern CPUs need a separate fan mounted on a heat-sink to remove all of the heat generated. Overheated parts generally exhibit a shorter maximum life-span and may give sporadic problems resulting in system freezes or crashes. PC Cooling is mainly done using heat sinks to increase the surface area which dissipates heat, fans to speed up the exchange of air heated by the computer parts for cooler ambient air, and in some cases soft cooling, or the throttling of the speed of some computer parts in order to decrease heat generation.

First a little thermodynamics review. A heat-sink is an object that moves heat from an object that it is trying to cool, to a lesser hot area or object. It absorbs heat from an object, and transfers that heat to another object or the surrounding air. In the computer, a heat-sink, usually made of aluminum, is placed in direct contact with the CPU chip. A thermal grease is used to help the heat transfer from the CPU chip to the heat-sink. The heat is then typically transferred to the ambient air (the lesser hot area). The heat sink helps cool the CPU by transferring heat from the CPU, at a relatively high temperature, to the ambient air, at a relatively lower temperature. This transfer of heat keeps the CPU from overheating and possibly shutting down. The most common design for a heat-sink is a piece of metal with many fins. The large surface area due to the fins results in the rapid transfer of heat to the surrounding, cooler air. A fan improves the transfer of heat from the heat-sink to the air by moving cooler air between the fins. This is how the combined heat-sink and fan work to cool down the CPU chip.

Now all that may seem a bit academic, but the point is that the components inside the PC must be cooled. You know how good you feel when you turn on a fan on a hot day. The heat-sinks and the fans are necessary for your computer to continue operating. So, if your fans stop or your heat-sinks stop being effective, your computer will eventually stop operating. If a fan stops it is usually easily noticed either by seeing it stopped when the computer is on or the lack of air flowing or the lack of the sound of the fan motor. It’s the heat-sinks operation that is hard to determine. The best way to discern the operation of the heat-sink is to look at it. (Yes, that means removing the cover.) It should be nice and shiny and new looking, and not covered with dust or animal hair. Dust covering the heat-sink will impede its ability to transfer heat to the air, even if the fan is moving the air over the dust laden heat-sink.

A visual check of the cleanliness of the heat-sinks every 3 to 6 months is advisable. (Maybe even more often if your computer is in a dusty environment, {like in the corner of a room on a rug}, and/or you have furry pets in the area.) Make sure you unplug the computer before you do this. While you are in there checking, take a can of “dust remover”, which is like compressed air, and blow out all of the dust you can see, especially around the CPU heat-sink. Also, make sure all of the inlets and exhaust holes in the case are free from dust and debris so that the normal air flow will not be disturbed. That can of “dust remover” is your best defense against dust buildup both on the heat-sink surfaces, and around the air holes. (Keep a can of dust remover close at hand and give a package of them to your computer owning friends during the holiday season.) Follow the directions on the can. Be especially careful not to hold the can on an angle or upside down, as doing so may force out a flammable freezing liquid. (Note that it is normal to feel the bottom of the can getting cold while the can is blowing air.) If you blow out the dust every 3 to 6 months, your computer should run nice and cool for many years, and you’ll be spared some very strange and possibly aggravating problems. © 2010 by Phil Sorrentino

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