Hardware Reference
In-Depth Information
About the only way to determine which company actually made a partic-
ular power supply is to check the UL label and look up the manufacturer
in a database. Here's one website that maintains such a list:
Some power supply manufacturers produce only cheap power supplies.
Some produce a wide range of models, from cheap to first-rate units. A
few produce only high-quality power supplies. Among the manufacturers
(as opposed to brand names) we've found to be consistently reliable are
Channel Well (USA), FSP/Sparkle, Seasonic, and Win-Tact.
Here are some less important things to consider when choosing a power
supply:
Modular power supply cables
Many power supplies have fixed power cables. If you're building a system
in a relatively large case, that's not a problem; there are plenty of places to
tuck unused power cables out of the way. But in smaller systems, space is
at a premium. The last thing you want is unused power cables cluttering
up the available space, blocking air flow and interfering with fans. That's
why some power supplies use modular cables. The cables that are always
required—the main power cable, the +12V motherboard power cable,
and perhaps one peripheral power cable—are permanently affixed to the
power supply. You can connect optional cables, such as the PCIe power
cable and additional peripheral power cables, only if you need them.
There are several jacks on the power supply body that accept PCIe power
cable(s) and additional peripheral power cables, allowing you to install
only those cables you actually need. Most modular power supplies come
with a good selection of optional cables, but if you need extra cables of
a particular type you can usually buy them separately from the company
that makes the power supply.
All other things being equal, a power supply that provides modular cables
is usually a bit more expensive than one that does not. More importantly,
it is also a bit less reliable, at least in theory, because it uses plugs and jacks
rather than soldered connections. On balance, we tend to use a modular
power supply when we build a small system and a standard power supply
when we build a full-size system, but the difference is not enough either
way to make it a major decision factor. Treat modular power cables as a
tiebreaker if you're choosing between two otherwise similar power sup-
plies. Otherwise, don't worry about them.
Efficiency
Typical power supplies of a few years ago had efficiencies around 70%,
which meant that 100W of AC input was required to provide 70W of DC
output, with the remaining 30W simply producing waste heat inside the
power supply. Most current power supplies are rated at 80% or higher ef-
ficiency, and the most efficient exceed 90%. The issue is not simply wasted
power and higher electricity bills; it's that waste heat. Heat is the enemy of
PCs, and it's worthwhile to reduce waste heat whenever possible.
