Hardware Reference
In-Depth Information
shorter its life. Many people recommend replacing the original supply in a system with a heavier-duty
model, which solves the problem. Because power supplies come in common form factors, finding a
heavy-duty replacement for most systems is easy, as is the installation process.
Inadequate Cooling
Some replacement power supplies have higher-capacity cooling fans, which can minimize
overheating problems—especially for hotter-running processors. If system noise is a problem,
models with special fans can run more quietly than the standard models. These power supplies often
use larger-diameter fans that spin more slowly, so they run more quietly but move the same amount of
air as the smaller fans. There are even fanless power supplies, although these are more expensive and
are generally available only in lower output ratings.
Ventilation in a system is also important. In most prebuilt systems, this is not much of a concern
because most reputable manufacturers ensure that their systems have adequate ventilation to avoid
overheating. If you are building or upgrading a system your own system, then the responsibility for
proper cooling falls on you. In that situation it's critical that your processor is cooled by an active
heatsink and that the case include one or more cooling fans for additional ventilation. If you have free
expansion slots, I recommend spacing out any expansion cards in the system to permit airflow
between them. Place the hottest-running boards nearest the fan or the ventilation holes in the system.
Make sure that adequate airflow exists around the hard disk drives, especially for those that spin at
high rates of speed. Some hard disks can generate quite a bit of heat during operation. If the hard
disks overheat, data can be lost.
Always be sure you run your computer with the case cover on, especially if you have an older, loaded
system using passive heatsinks. Removing the cover in that situation can actually cause the system to
overheat. With the cover off, the power supply and chassis fans no longer draw air through the
system. Instead, the fans end up cooling only the supply, and the rest of the system must be cooled by
simple convection. Systems that use an active heatsink on the processor aren't as prone to this type of
problem; in fact, the cooler air from outside the normally closed chassis can help them to run cooler.
In addition, be sure that any empty slot positions have the filler brackets installed. If you leave these
brackets off after removing a card, the resultant hole in the case disrupts the internal airflow and can
cause higher internal temperatures.
Finally, the location of the system can have an effect on cooling. I don't recommend placing a system
on a carpeted floor, as most chassis are designed to draw in air at the bottom of the front bezel, which
can easily be blocked or become clogged with carpet fibers. Another problem is that a system sitting
directly on a floor will ingest a large amount of dust and debris, even more so if the floor is carpeted.
If you must place a system on the floor, whether it is carpeted or not, I recommend elevating it at least
an inch or so via some sort of platform.
If you experience intermittent problems that you suspect are related to overheating, upgraded chassis
fans or a higher-capacity replacement power supply are usually the best cures.
Using Digital Multimeters
One simple test you can perform on a power supply is to check the output voltages. This shows
whether a power supply is operating correctly and whether the output voltages are within the correct
tolerance range. Note that you must measure all voltages with the power supply connected to a proper
load, which usually means testing while the power supply is still installed in the system and
