Hardware & Infrastructure
11:18 AM
Fred Langa
Fred Langa
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The Explorer: None Like It Hot

Excessive heat is a CPU's worst enemy. Here are software utilities that can help.

Have you ever touched the surface of a working computer's CPU chip -- say, a Pentium or an Athlon? These days, they get hot enough to take off your fingerprints.

Fortunately, it's not that easy to touch the surface of a working central processing unit: Almost all CPUs are covered with heat-sink-and-fan assemblies that help dump the chip's heat into the air inside your computer's case, from which it's vented out by one or more additional fans.

You see, heat is the enemy of a CPU chip. The cooler a CPU chip is kept, the more stable it is and the longer it lasts " it's as simple as that. At abnormally high temperatures, a CPU may behave erratically or lock up; if you're lucky, normal operation will resume when things cool off. But a single extreme temperature spike, or long, frequent periods of running "outside thermal spec," can permanently damage or destroy a CPU.

Thermal management in personal computers -- and CPUs in particular -- used to be a fairly forgiving science with a wide range of acceptable, roughly-engineered solutions. Early PCs had one fan inside the power supply, for example, to handle cooling for the entire system. But as CPUs got faster and more advanced, they pumped more and more energy through smaller and smaller wire traces at ever-increasing clock frequencies. The result is that today, without properly-sized and functioning heat sinks and fans, most CPUs would literally cook themselves to death in short order.

That's why so many current desktop PC designs internally resemble miniature wind tunnels: The higher-end and faster your PC, the more fans it's likely to have.

The 1.2GHz PC sitting at my feet, for instance, has no less than five fans busily whirring away: a very large fan ventilating the case as a whole, a smaller fan ventilating the power supply (and, to a lesser degree, the case), a medium-sized fan blowing air down through the CPU's massive heat sink, and a pair of tiny fan/heatsinks mounted on other chips -- one on the video card's graphics processor, and one on the motherboard's largest chip.

Although the main focus of this article is desktop PCs, laptops also can run hot, but usually not as hot as full-sized desktop units. That's because laptops use special lower-voltage components and aggressive power-saving technologies, and usually run at lower speeds than top-of-the-line desktop models. Many laptops can get by with smaller fans, or even no fans at all (as can some special desktop designs). One common trick laptops use is to dissipate heat through the laptop's housing, using the metal case as a heat sink -- often to the chagrin of travelers on long-duration plane flights, who find their thighs getting singed by the excess heat pouring out through the bottom of their laptop.

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