Putting the hush on that PC noise takes effort

We live in a world of PC noise pollution, but I'd never realized how bad it was until I bought my last computer. Like most of us, I'd assumed that all PCs hummed and whined -- the price we pay for the fans that keep all those hot new chips from frying.

But this computer -- a Compaq Presario -- was different. True, when I turned it on, it hummed and whined like every other PC, but after two minutes it settled down to well, something close to silence.

At first I thought the machine was broken, so I put my ear to the case, and sure enough, there was a very soft hum. But from a foot away, it was virtually inaudible. That's when I realized why the power light on the front was so large and bright -- without it, you can't tell whether the machine is running.

This wasn't a particularly expensive PC, but it's an example of good, user-friendly design. As I used it, from time to time I'd notice that the big fan in the back of the case would start whirring, but only for a minute or two until the interior temperature cooled down.

I also realize how spoiled I've become by all this silence whenever I turn on my backup computer -- a plain vanilla eMachines model that never bothered me before. Now the racket it kicks up is intolerable. The same for my wife's Dell, and even the big-screen laptops my kids use.

It's something to think about next time you buy a computer. True, it's hard to tell how noisy a machine is in a big box computer store, where the ambient noise is equal to the average train station. But it's definitely worth putting your head close to the machine and cycling the power off and on again to hear how much noise it adds to its surroundings.

There are also steps you can take to deal with noise from an existing PC. If you have a tower unit sitting on your desktop, you can try moving the machine to the floor next to the desk or under it.

Moving the machine a foot or two away, or placing a desktop between you and the noise, can help. The main downside to this solution is convenience. If you frequently use CDs or your machine has a digital memory card reader, bending down to change media can be a pain.

If your PC sits on the desktop, consider putting a rubber mat underneath. Vibration can echo through a wooden desk and make a computer seem even noisier than it is. But the real cure is likely to involve minor surgery -- specifically, a fan-ectomy and transplant.

Most PCs have at least three fans -- a big one for the power supply and smaller fans for the processor and the case. Faster PCs with hotter components may have extra fans to cool the case, and some, including high-end gaming PCs and the quiet Mac G5, supplement their fans with liquid cooling systems that work like automobile radiators.

The most likely culprit in a noisy computer is the power supply, a silver box located in the top rear corner of most tower PCs. The power supply houses the transformer that turns 110-volt alternating household current into the low-voltage direct current that PC components need to operate.

A transformer by its nature generates a lot of heat, and the fan that cools the power supply has to be capable of moving a lot of air. You can move a lot of air relatively quietly with a good fan, or noisily but just as effectively with a cheap one.

A new PC that makes a lot of noise probably does so because the manufacturer decided to save money there, but even a decent fan can degrade after a year or so and start whining.

Fortunately, low-noise replacement power supplies are readily available and not outrageously expensive -- from $75 to $120 in computer stores or on the Web. Many use two or more small fans to maximize air flow and minimize the racket.

If you're adventurous and reasonably handy with a screwdriver, replacing a noisy power supply isn't brain surgery. It involves unplugging the computer, disconnecting the leads from the power supply to the various components it serves (the main circuit board and disk drives) and removing the screws that attach the power supply to the case.

But before you even think about doing that, find a low-noise replacement that matches your computer's power requirements and configuration. There's no guessing here -- close doesn't count. The wrong power supply may not fit in the case or have the specific connector your computer's motherboard needs. If you can supply the make and model of your PC, and better yet, the model number from the label attached to the original power supply, most vendors can match it with a low-noise model.

The second critical step, once you've installed the new power supply, is making sure that you run the right leads to the right components again.

If all this sounds too much like work, many shops will do the job for the minimum repair charge -- $60 to $100, plus the cost of the hardware. So a power supply is not a cheap replacement, but if it keeps an otherwise useful computer from driving you nuts, it's money well spent.

Smaller fans that cool the case and CPU are generally quiet.