Multimeter-Based Selection Method for Computer Power Supplies
Choose a Robust‑Performing Power Unit - How to Select a Computer Power Supply with a Multimeter
Nowadays, new‑generation components such as graphics cards, sound cards, optical drives and hard disk drives all consume considerable power. When you fill your PC with plenty of hardware, have you ever considered equipping it with a reliable power supply as its "heart"?
Plenty of expert opinions regarding power‑supply identification have been published in magazines and newspapers, which can be summed up in three approaches:
First, visual inspection - Check whether the power supply uses high‑quality components, exhibits fine workmanship and has a reasonable internal layout. Frankly speaking, this method can be quite demanding. For one thing, it requires solid electronics knowledge. For another, you have to remove the power‑supply cover to examine its internal parts thoroughly. This will break the manufacturer's warranty seal, which automatically voids warranty coverage. Once the seal is broken, you will have to repair it yourself even if the power supply malfunctions. Many ordinary beginners have been forced to become experienced tinkerers out of sheer desperation.
Second, tactile check - After the power supply has run for a period of time, feel whether the air blown out by its fan is scorching‑hot and whether the casing gets too hot to touch.
Third, smell test - Sniff for burnt odors after prolonged operation. The latter two methods rely purely on accumulated subjective experience. How can novices make sound judgments without such experience? Here, a multimeter‑based method for evaluating power‑supply quality is recommended, which may offer some help for beginners.
First of all, obtain a multimeter (preferably a digital one) and learn how to operate it. An ATX power supply mainly outputs 3.3 V, 5.0 V and 12.0 V. Among these, the 12.0 V rail provides primary power for hardware devices and shows the most noticeable voltage variation under heavy loads. After connecting all computer loads, pick an unused output connector. Insert the black probe into the black‑wire socket and the red probe into the yellow‑wire socket to measure the 12 V output voltage. Connect all the connectors properly and power on the computer for measurement. The multimeter readings will fluctuate and stabilize only once the operating system fully boots up. Record the stable voltage value. Under normal conditions, it should stay around 12 V (within approximately 11.95 V ~ 12.15 V). Too low a voltage cannot sustain stable long‑term operation under heavy loads and leaves no headroom for hardware expansion. Excessively high voltage will cause components to heat up and age prematurely.
