Hardware Reference
In-Depth Information
shapes, screw-hole positions, connector types, and fan locations. When ordering a replacement
supply, you need to know which form factor your system requires.
Some systems use proprietary power supply designs, which makes replacement more difficult. If a
system uses one of the industry-standard form factor power supplies, replacement units with a variety
of output levels and performance are available from hundreds of vendors. An unfortunate user of a
system with a nonstandard form factor supply does not have this kind of choice and must get a
replacement from the original manufacturer of the system—and usually must pay a much higher price
for the unit. PC buyers often overlook this and discover too late the consequences of having
nonstandard components in a system.
See “
Power Supply Form Factors
,”
p.
849
.
Name-brand systems on both the low and high end of the price scale are notorious for using
proprietary form factor power supplies. For example, Dell has used proprietary supplies in many of
its systems. Be sure you consider this if you intend to own or use these types of systems out of
warranty or plan significant upgrades during the life of the system. Where possible, I always insist on
systems that use industry-standard power supplies, such as the ATX12V form factor supply found in
most systems today.
With backward compatibility ensuring that the 24-pin ATX power connector will plug into older 20-
pin motherboard sockets, when purchasing a new power supply, I now recommend only those units
that include 24-pin main power connectors, which are usually sold as ATX12V 2.x, EPS12V, or “PCI
Express” models. For the most flexible and future-proof supply, also ensure that the power supply
includes two or more PCI Express graphics connectors as well as multiple integrated SATA drive
power connectors. Choosing a power supply with these features provides flexibility that allows it to
work not only in modern systems, but also in virtually all older ATX systems—and with no adapters
required.
See “
ATX12V 2.x 24-pin Main Power Connector
,
”
p.
877
.
As a guide, here are some of the features I recommend looking for in a PSU:
• Adequate power connectors (24-pin main, 4/8-pin +12V CPU, 6/8-pin PCIe Graphics, SATA,
and so on) for the intended system
• Adequate power output (watts) for the intended system
• 80-plus certification
• Active Power Factor Correction (required with 80 PLUS)
• SLI or CrossFire certification
• Single +12V rail design
There are other variables to consider, depending on your specific needs or desires. One feature that
many people like is modular cables, which minimize the clutter in a system. Another feature to
consider is noise, which is mostly related to cooling. The type and arrangement of cooling fans has a
great effect on how quiet (or noisy) the unit will be. There are even some fanless units that are
completely silent, but these usually come at a premium price and with a lower overall power output
capability.
When building systems with case windows, some people also like to look for PSUs with appearance-
related features like colored cases.
