Summertime and the CPU Chip’s Overheating

As summer approaches, your PC has two new enemies: heat and potential electrical problems.

Heat has historically been a problem for computers, which is why large mainframe and mini-computers were kept in air-conditioned rooms. PCs don’t generally need to be kept under refrigeration, but they can act up if the environment gets too hot. You probably won’t have any problems as long as the temperature stays below 85 or so. But when it gets really hot, you might suddenly find your PC working erratically or not at all. This is especially true with high-speed Pentium machines--the faster the CPU, the hotter it’s likely to get.

If you have a problem you suspect is heat-related, the best thing to do is turn off the machine for half an hour or so and see if things start working normally again. If so, it’s a good bet that heat is the problem.

If you can, cool down the room. The machine--as well as you--is likely to work better. But even if you can’t do anything about the general room temperature, you might be able to cool things down for the PC by being sure there is plenty of room around the unit for ventilation and, if necessary, putting a small table fan in the general vicinity of the PC to cool off the immediate area. Be sure the fan is well clear of the machine itself and any cables.


Just about all personal computers have a built-in fan, but it isn’t always adequate, especially when the room temperature approaches triple digits. The hottest component in the system is the central processing unit (CPU) chip, which, in the case of a 100-megahertz or higher Pentium, can get hot enough to burn your finger if you touch it.

Some manufacturers cool off the CPU by adding a heat sink, which is basically heat-absorbing material that attaches to your CPU and helps dissipate heat into the air. Heat sinks can help, but if the chip is generating too much heat in a room that’s already sweltering, you can still have problems.

In that case, you should add a small CPU fan, which, in most cases, sits on top of the CPU and blows air directly onto the chip, dissipating the heat into the case, where it is expelled by the machine’s main fan. These CPU fans, which cost as little as $15, are pretty easy to install and generally do the trick.

Alpha & Omega Computer of Placentia, Calif. ([800] 838-5868 or, manufactures and sells a variety of heat sinks and cooling fans priced between $5 and $60. The fans, by the way, take their power from the PC’s power supply, using the same cables that provide power to disk drives.


Notebook computers can also get pretty hot, especially those with a Pentium CPU. Some notebook PCs don’t have an internal fan, which is usually OK for 486 or even 75-MHz Pentiums, but if you’re shopping for a machine with a 90-MHz or higher Pentium CPU, be sure it has a fan.

Heat is a particular problem if you’re using the notebook on your lap, as it’s easy to block off air circulation.

In certain parts of the country, summer is also the season when you’re most likely to have power-related problems. Thunderstorms can cause power failures and, in rare cases, major electrical surges if lightning strikes a nearby line or transformer.

It’s also the most likely time for power brownouts caused by heavy use of air conditioners. That’s why it’s essential to have a surge protector and why uninterrupted power supplies (UPS) are becoming popular.


A UPS is an external device with a built-in battery that keeps the PC running for a few minutes even if the power has been turned off. It doesn’t give you enough time to continue working, but you do have time to save your files and shut down the machine.

American Power Conversion’s ([800] 877-4080 or Synergi (about $150) combines a battery-powered UPS for your PC, monitor and one other device along with a built-in surge suppressor for your PC, telephone and other computer equipment. The battery will keep your PC running for about seven minutes, which is enough time to save your files and shut down the system.

Even if the power doesn’t fail completely, the device will kick in in the event of a brownout, when voltage starts to diminish. Other companies that make UPS systems include Best Power Technology ([800] 356-5794), Hewlett-Packard ([800] 533-1333) and Intellipower ([714] 587-0155).

If you plan to take a notebook computer on an airplane this summer, be especially cautious as you go through the security checkpoint, especially if the person in front of you is blocking your view of the conveyor belt. Some thieves work in pairs. One person deliberately sets off the metal detector to cause a distraction while the other one grabs your briefcase. Don’t put your bag on the belt until you have a clear view of the other side.


I don’t recommend that you use your notebook computer while you drive, but if you are going on a trip, you can recharge your batteries by plugging a power inverter into your cigarette lighter. I bought one at an electronics store for about $40.

Lawrence J. Magid can be reached via e-mail at His World Wide Web page is at