Power supplies are a frequently misunderstood--and overlooked--PC component. Many users choose a power supply based on total wattage alone, assuming that higher is always synonymous with better. Others pay no attention to their PSU selection at all, and settle for whatever abomination arrived with their machine. But considering how important a good power supply is to a system's stability and long-term reliability, it's a shame that PSUs get so little attention in comparison to sexier components like graphics cards and SSDs.
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It doesn't help that the power-supply market is awash with products from unscrupulous manufacturers that use substandard components and overstate the hardware's capabilities. Indeed, the abundance of PSU-related misinformation and deception in the marketplace would be comical if it weren't so harmful to consumers. But finding a solid, efficient power supply is possible if you arm yourself with the right knowledge. We can help.
Choosing a power supply
There is no single, universal rule for selecting a high-quality power supply. Nevertheless, various indicators provide circumstantial evidence of PSU quality, and some guidelines are generally helpful.
First, always buy a power supply from a reputable manufacturer, and look for reviews of it before you buy. Avoid cheap, generic power supplies, which tend to be substandard. Look for reputable brands that offer solid warranties and support. Corsair, Seasonic, and Antec are three manufacturers with reputations for producing high-quality power supplies, though even they may offer a few duds among all the studs. Do your homework!
Larger, heavier units are preferable to puny, lightweight models. Higher-quality power supplies almost always use bigger and better capacitors, chokes, and other internal components, and they come outfitted with larger heatsinks for superior heat dissipation--all of which translates into more weight. Larger cooling fans, which typically move more air while making less noise than smaller fans, are another plus.
Of course, you should also check the PSU's connectors to confirm the unit is compatible with your particular system. The term 20+4 pin refers to a connector that can function as either a 20-pin connector or a 24-pin connector. In the 6+2 pin connector shown at right, you can snap two of the pins in the connector on or off to suit your needs.
The vast majority of consumer PCs use standard ATX power supplies. Smaller units and units specially designed for enterprise and server applications are also available; but for common desktop systems, ATX power supplies are it.
When searching for a power supply, keep your eyes on three crucial features: power output, rails, and efficiency. Other specifications and features are important, too, but these three directly affect the PSU's performance.