Why 99% of Power Supply Reviews Are Wrong

Zitat

With computers (and users) asking for better power supplies, nothing more natural than reviewing websites publishing power supply reviews. But contrary to other hardware parts like CPUs, motherboards and video cards, one must have deep electronics knowledge in order to test a power supply. Since most reviewers are simply users with a above-the-average knowledge in computers – but not in electronics – almost all PSU reviews posted on the web are completely wrong and they do more harm than good, as some websites recommend products that are really flawed. In this article we will explain in details why 99% of power supply reviews posted on the web are wrong and we hope that reviewers learn more about the subject by reading this article and also that users learn how to identify a bad review.

[...]The idea of measuring a power supply with a multimeter comes from linear power supplies, where the power supply has a separated voltage regulator circuit (normally done by an integrated circuit or by a zener diode, sometimes with the aid of a power transistor). In this kind of power supply it makes sense to use the multimeter to check whether the regulator circuit is working fine or not. Even in this case, simply attaching the multimeter won’t let you know if the power supply is being able to provide its labeled current/power. You will need to add a load to the power supply outputs.

On linear power supplies, as they are an open-loop system (more about this in a moment), the output voltage can increase or decrease accordingly to the applied load – so the idea of attaching a multimeter in parallel with the load to check if there is any voltage fluctuation depending on the load makes sense.