Hardware Reference
In-Depth Information
Variablevoltagetransformersaresoldbyanumberofelectronicpartssupplyhouses,such
as Newark and Digi-Key.
Power Supply Recommendations
When you are shopping for a new power supply, take several factors into account. First,
consider the power supply's shape, or form factor. Power supply form factors can differ
in their physical sizes, 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 dif-
ficult. If a system uses one of the industry-standard form factor power supplies, replace-
ment 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 sys-
tem.
See Power Supply Form Factors ,” p. 837 (this chapter).
Name-brand systems on both the low and high end of the price scale are notorious for
usingproprietaryformfactorpowersupplies.Forexample, Dellhasusedproprietarysup-
plies 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 sys-
tem.Wherepossible,Ialwaysinsistonsystemsthatuseindustry-standardpowersupplies,
such as the ATX12V form factor supply found in most systems today.
With backward compatibility ensuring that the new 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 usu-
ally 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. Choos-
ing a power supply with these features provides flexibility that allows it to work not only
in newer systems, but also in virtually all older ATX systems—and with no adapters re-
quired.
See ATX12V 2.x 24-pin Main Power Connector ,” p. 864 (this chapter).
As a guide, here are some of the features I recommend looking for in a PSU:
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