Short answer: the surest test is swapping in a known-good power supply. A power supply tester is the next best thing and cheap to buy. The jumper test only tells you the unit can turn on, not that it’s healthy under load.
The four methods
| Method | What it tells you | Difficulty |
|---|---|---|
| Swap test | Whether the fault follows the power supply | Easy if you can borrow a unit |
| Power supply tester | Voltages on each output, and power-good timing | Easy |
| Multimeter | Voltages on the 24-pin plug, with no load | Moderate |
| Jumper (paperclip) test | Whether the unit turns on at all | Easy, but take care |
Swap test
Borrow a suitable power supply and connect it with its own cables. If the fault goes away, your old unit is to blame. If it doesn’t, look at the graphics card, memory or motherboard. Never mix cables between the two units.
Power supply tester
Corsair describes the steps. Connect the 24-pin and CPU cables to the tester, plug in the mains, and switch on. The screen shows the voltages. Lights confirm power on SATA and other plugs.
Corsair notes two things that can look like faults but aren’t:
- Newer units have tighter power-good timing, so some older testers flag them wrongly.
- Newer units dropped the -12V output, so a tester may show a strange reading on it.
Multimeter
Set the meter to DC volts, put the black probe on a ground pin of the 24-pin plug, and touch the red probe to each voltage pin. Corsair’s guide lists the pins. Readings well away from 12V, 5V and 3.3V point to a fault. This test is done without load, so a unit can pass and still fail in a game.
Jumper test
Corsair describes this for checking that a unit turns on. Switch off and unplug everything except the mains and 24-pin cable. Bridge pins 16 and 17 on the 24-pin plug, which are the 4th and 5th pins from the left with the clip facing up, then switch on. If the fan spins, the unit is turning on.
Corsair warns that bridging the wrong pins can damage the unit or injure you. If you aren’t confident, use a tester instead.
What none of these test
None of these home tests check behaviour under heavy load or during spikes. A unit that passes can still shut down while gaming. If that’s your problem, see PC shuts off under load.
Never open it
Capacitors inside can hold a dangerous charge after the unit is unplugged. Opening it also voids the warranty.
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Questions
Is the paperclip test safe?
Corsair describes it, with a warning that the wrong pins can cause damage or injury. A tester is safer.
Can a power supply pass a test and still be faulty?
Yes. Home tests don’t check heavy loads or spikes.
What should the voltages read?
Close to 12V, 5V and 3.3V on the matching pins. Big differences point to a fault.
Are power supply testers accurate?
Good enough to spot a dead output or badly wrong voltage. They don’t test under load.
My tester says power-good fails on a new unit. Is it broken?
Not necessarily. Corsair notes newer specs use tighter timing that some testers flag.
Sources
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