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IT Support & Hardware · Foundational

Power Supply Tester

A device that checks a PSU's output voltages on each connector without a motherboard.

Definition

Plugging the 24-pin and other connectors into a PSU tester shows whether rails are within tolerance (typically 5%) and whether the power-good signal is present. A multimeter can also measure individual pins. Testers do not test performance under full load.

Example

A tester shows the +12 V rail at 11.2 V, outside tolerance, indicating a failing PSU.

Exam tip

Use a PSU tester or multimeter to confirm a suspected power supply failure before replacing the motherboard.

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