Overheating may cause computer shutdown

November 03, 2005|By MIKE HIMOWITZ

Over the last couple of weeks, I've heard several complaints from readers about computers that behave strangely after several hours of hard use.

Sometimes they slow down and the screens may start to blink. Then they shut off. When the owners wait a half-hour and turn them on again, everything's just fine - for a while. Until it happens again.

While it's impossible to diagnose all hardware problems via e-mail, these sound a lot like overheating. I have no hard data on this, but it seems to be more common as users keep older PCs running longer and as newer PCs run hotter and hotter.

In fact, not long ago, I reviewed a new gaming laptop that shut itself down sporadically whenever we tried to run The Sims at the game's highest resolution. Of course, I couldn't use it very long under any circumstances because the top of the case was too hot to type on.

But that's nothing compared with what happens when you actually put one of the digital pizza ovens on your lap. In fact, new research shows that extra-hot laptops may actually endanger the species.

More about that later. Let's talk about what's happening inside.

Consider that your computer was designed to produce heat. Its microprocessor, support circuitry and memory chips contain millions of transistors that are refreshed with electrical charges literally billions of times per second. Even at a low voltage, all that activity generates resistance and lots of heat. The faster your computer runs, the more heat it generates. Just converting the 120-volt alternating current from your wall outlet into the low-voltage direct current that your computer uses creates heat, too.

Early desktop computers, such as the Apple II, managed to disperse the heat through vents in the case. But as chip counts grew, manufacturers added a fan to circulate air through the circuit boards and carry off the heat from the power supply. Then they added a fan for the processor, and fans for the video card, and more fans to vent the case.

Today it's not unusual for gaming machines to advertise a half-dozen or more fans. And a few, including Apple's G5 desktops, have liquid cooling systems - the PC equivalent of automobile radiators.

On the whole, these desktop cooling systems do a good job. Otherwise, we'd all be in meltdown. But occasionally a fan will fail, and you may not notice it. Or dust may build up inside the case, blocking the fan vents. A PC kept on a shelf or in a cubbyhole of one of those computer desks where there isn't enough room for air to flow around the case can also be in trouble. Now and then, a faulty chip mounting or other design flaw will allow heat to build up.

When the temperature gets too high, most PCs will do one of two things. Newer machines may increase fan speed and throttle back processor speed. If those precautions don't reduce the internal temperature, or those features aren't available, most computers will shut themselves off rather than go into meltdown.

Laptops are even more disadvantaged, because their components are crammed into less space than a desktop PC's. Although their power supplies are usually external bricks, eliminating one source of heat in desktop computers, laptop batteries add almost as much heat to the mix.

Designers have compensated for crowded laptops by creating lower-powered versions of their processors and other chips. They conserve battery life and reduce heat - but they also account for portables that are more expensive and not as fast as desktops.

To save money where battery life isn't important, some laptop makers use standard processors instead of low-powered versions. That's even worse.

In any case, the net result is lots of heat. Once silent except for the click of their hard drives, most laptops now have at least one fan, and high-end gaming models have four or five.

Even so, laptops are often warm to the touch, and downright uncomfortable if you use one on your lap for more than a few minutes. One of my colleagues refers to his laptop as "a hibachi that gets e-mail."

Although there are sporadic reports of laptops catching fire (usually the result of faulty batteries), this year researchers at the State University of New York at Albany came up with an entirely new threat. They found that laptops generate enough heat to reduce male sperm counts when the computer was used on the lap for extended periods. They theorized that the popularity of laptops could well be contributing to an overall drop in male fertility.

We won't take this any further - other than to recommend an accessory known as the laptop desk - a portable tray that provides a stable lap platform for a computer as well as a heat barrier. I've tried a few, and they're a lot more comfortable than being top-browned by your PC.

So what do you do with an overheating computer?

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