01.Electrical Diagnosis: Is the PC Still 'Alive'?
In 2026, with graphics cards demanding more and more power, the power supply unit (PSU) has become the component that most often fails silently. The PC might turn on the LEDs but fail to display video due to a lack of stable voltage on the 12V rail. Using a multimeter is the only way to ensure your PSU is not "dying" and putting your other expensive components at risk.
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02.1. The Paperclip Test (Power On)
First, we need to make the PSU turn on without being connected to the motherboard:
- Unplug the power supply from the wall and remove all cables from the PC.
- On the large 24-pin connector, locate the single Green Wire (PS_ON).
- Use a paperclip to connect the green wire pin to any adjacent Black Wire (GND).
- Plug the PSU into the outlet. If the PSU fan spins, it's receiving power.
03.2. Measuring Voltages with the Multimeter
Reference Values in 2026:
Set the multimeter to the 20V DC scale. With the PSU turned on (using the paperclip test):
- Yellow Wire: Should read between 11.4V and 12.6V. If it's below 11.4V, your PSU won't handle a heavy graphics card.
- Red Wire: Should read close to 5.0V.
- Orange Wire: Should read close to 3.3V.
- Purple Wire: (5V Standby) Should have 5V even when the PSU is in standby.
04.3. Symptoms of a Faulty Power Supply
When to replace the PSU?
If the voltages fluctuate significantly (e.g., the 12V rail dips to 11V and back), your PSU's capacitors are worn out. In 2026, an unstable PSU causes the infamous spontaneous reboot: your PC shuts down suddenly while playing a demanding game because the voltage drops below the safety threshold, and the motherboard cuts power to protect itself.
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Written by a verified expert
Douglas Felipe M. Gonçalves
Expert in Windows system optimization with years of experience in hardware diagnostics, kernel tuning, and advanced technical support. Founder of Voltris and developer of the Voltris Optimizer.
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By following this guide on How to Test a PC Power Supply with a Multimeter (2026 Guide), you are equipped with the verified technical knowledge to solve this issue with confidence.
If you still have difficulties after following all steps, our expert support team is available for a personalized remote diagnosis. Every system is unique and may require a specific approach.