How Much Power Can a Generic 500 W Power Supply Really Deliver?

Conclusions

In this review we proved what everybody already knew: that generic power supplies cannot deliver their labeled power. Worst than that: manufacturers deliberately lie about the power supply power rating, as there is no math in the world that explains how a 250 W power supply can be labeled as 500 W.

We also showed you the main differences between a generic power supply and a “branded” one and where the manufacturer cut costs. Generic power supplies use thinner wires outside and inside the power supply, they simply don’t have a transient filtering stage, they use cheaper components with lower current/power limits, they don’t have additional but important protections like overload protection and they simply remove components (electrolytic capacitors and coils) from the power supply filtering section, what increases the noise level on the power supply outputs.

Noise
level is the main problem with generic units. On this generic power supply we reviewed noise level was outside specs at any wattage we pulled from the power supply. When pulling 250 W from this unit, noise level at +5 V was at 220 mV, more than four times above the limit.

This explains why some stability problems (i.e., computer freezing, computer rebooting by itself, etc) on computers using a generic power supply are solved by replacing the power supply with a “branded” one, even when your computer isn’t pulling a lot of power.

The bottom line: avoid generic power supplies. Even entry level computers should use a decent “branded” power supply. Most manufacturers provide cheap entry-level models below USD 50 that will provide clean outputs and make your computer to work fine and protect its components from damaging – so the price excuse is simply inadmissible. So moving from a generic power supply to a branded one isn’t only about allowing your computer to pull more power, but also providing cleaner voltages to it.

Even though with educational information provided by our website and several others on the web the computer power supply is still the most neglected component in the PC. Several users are very picky about all other components for their new PC but when it comes to the power supply they simply choose the cheapest one. Of course you don’t need to buy an expensive high-wattage power supply for a mainstream PC, but using a generic one can really hurt your PC – who likes to have a PC that crashes all the time?

This review also helps us to explain why 99% of power supply reviews posted around the web are wrong. Most “reviewers” simply test power supplies by installing them on a PC and measuring voltages with a multimeter. Not only a typical PC won’t pull the amount of power necessary to say whether a given power supply can really deliver its rated power or not, but by just using a multimeter these “reviewers” don’t have any idea of the noise level on the power supply outputs, several times saying that a power supply is good just because the manufacturer was nice enough to send them a free sample when in fact the power supply is flawed as it is producing too much noise that can make the computer to work unstable.