Hardware Reference
In-Depth Information
In Canada, electric and electronic products are certified by the Canadian Standards Agency (CSA).
The German equivalents are TÜV Rheinland and VDE, and NEMKO operating in Norway. These
agencies are responsible for certification of products throughout Europe. Power supply manufacturers
that sell to an international market should have products that are certified at least by UL, the CSA, and
TÜV—if not by all the agencies listed, and more.
Apart from UL-type certifications, many power supply manufacturers, even the most reputable ones,
claim that their products have a Class B certification from the Federal Communications Commission
(FCC), meaning that they meet FCC standards for electromagnetic and radio frequency interference
(EMI/RFI). This is a contentious point, however, because the FCC does not certify power supplies as
individual components. Title 47 of the Code of Federal Regulations, Part 15, Section 15.101(c) states
the following:
The FCC does NOT currently authorize motherboards, cases, and internal power supplies.
Vendor claims that they are selling “FCC-certified cases,” “FCC-certified motherboards,” or
“FCC-certified internal power supplies” are false.
In fact, an FCC certification can be issued collectively only to a base unit consisting of a computer
case, motherboard, and power supply. Thus, a power supply purported to be FCC-certified was
actually certified along with a particular case and motherboard—not necessarily the same case and
motherboard you are using in your system. This does not mean, however, that the manufacturer is
being deceitful or that the power supply is inferior. If anything, this means that when evaluating power
supplies, you should place less weight on the FCC certification than on other factors, such as UL
certification.
Power-Use Calculations
When expanding or upgrading your PC, ensure that your power supply is capable of providing
sufficient current to power all the system's internal devices. One way to see whether your system is
capable of expansion is to calculate the levels of power consumption by the various system
components in your system and then compare that to the rating on the power supply to see if it is up to
the job. This calculation can also help you decide whether you must upgrade the power supply to a
more capable unit. Unfortunately, these calculations can be difficult to make accurately because many
manufacturers do not publish detailed power consumption data for their products. In some cases, you
can find the specs from a similar component and go by that data instead. Usually, components of the
same basic design, capability, and vintage have relatively the same power consumption
characteristics. Table 18.24 shows the range of power usage for typical PC components I've
observed over the past few years.
Table 18.24. Power Consumption Calculation
 
 
 
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