Guide for Selecting PC Power Supplies by Means of Multimeter
First check - Examine whether the power supply adopts high‑quality materials, fine workmanship and a reasonable layout. Frankly speaking, this method is somewhat impractical. To begin with, it requires sufficient electronics knowledge from the operator. Besides, to fully inspect all internal components of the power supply, you have to remove its housing case, which will inevitably break the manufacturer's warranty seal. Once the seal is broken, the official warranty becomes void. Even if the power supply malfunctions, you will have to repair it by yourself. Many beginners have been forced to become skilled hands out of sheer necessity.
Second check by touch - After the power supply runs for a period of time, feel whether the air blown out by its fan is scorching hot and whether the housing feels burning‑hot to touch.
Third check by smell - Sniff for burnt odors generated after the power supply operates for an extended period. The latter two methods rely entirely on subjective accumulated experience. Lacking such experience, how can new users draw valid conclusions? Here I recommend a method for evaluating power‑supply performance with a multimeter, which may be helpful for beginners.
First of all, get a multimeter (a digital one is preferred) and master its operation. An ATX power supply mainly outputs 3.3 V, 5.0 V and 12.0 V. Among these, the 12.0 V rail supplies main power for hardware devices and shows the most noticeable voltage shift under heavy loads. After connecting all computer loads, pick one spare output connector. Insert the black probe into the black‑wire terminal and the red probe into the yellow‑wire terminal to measure the 12 V output voltage.
Power on the computer for measurement once all connectors are properly seated. The multimeter readings will fluctuate and stabilize only after the system boots completely. Record the steady‑state voltage value. Normally it should hover around 12 V, within the range of approximately 11.95 V‑12.15 V. Too low a voltage cannot guarantee long‑term stable operation under heavy loads and leaves little upgrade headroom; excessive voltage will cause component overheating and premature aging.
