Introduction to Selecting a Computer Power Supply with a Multimeter
Nowadays, new‑generation components such as graphics cards, sound cards, optical drives and hard disks are all high‑power‑consuming devices. When you fill your PC with numerous hardware parts, have you ever considered equipping it with a robust power supply?
Plenty of expert opinions on identifying good‑quality power supplies can be found in newspapers and magazines, which can be summed up into three general methods.
First, visual inspection: Check whether the power supply uses high‑quality components, features fine craftsmanship and has a reasonable internal layout. Frankly speaking, this method is somewhat demanding. For one thing, it requires sufficient electronic knowledge. For another, you have to remove the power‑supply cover to observe its internal components thoroughly. This will inevitably break the manufacturer's warranty sticker, which automatically voids the warranty. You will have to troubleshoot it yourself even if the power supply malfunctions. Many ordinary beginners are forced to become experienced users out of helplessness in this way.
Second, tactile test: After the power supply has been running for a period of time, feel whether the air blown out by its cooling fan is scorching‑hot and whether the casing gets too hot to touch.
Third, smell test: Sniff for burnt odors after prolonged operation of the power supply. The latter two methods rely purely on accumulated sensory experience. How can novices make judgements without relevant experience? Hereby, I recommend a method for evaluating power‑supply performance by using a multimeter, which may offer some guidance for beginners.
First of all, obtain a multimeter (a digital multimeter is preferred) and master its operation. An ATX power supply mainly outputs 3.3 V, 5.0 V and 12.0 V. Among them, the 12.0 V rail provides major power for hardware devices and shows the most noticeable voltage fluctuation under heavy loads. After connecting all computer loads, pick one spare 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. Power on the computer once all connectors are properly attached. The multimeter readings will keep fluctuating and stabilize only after the system boots completely. Record the voltage value at this moment. Normally, it should stay around 12 V (approximately between 11.95 V and 12.15 V). Too low a voltage cannot guarantee long‑term stable operation under heavy loads and leaves little room for hardware expansion; excessively high voltage will cause overheating and premature aging of electronic components.
