PSU Paperclip Test Step-by-Step | Generated by AI

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Question: Walk me through exactly how to do the PSU paperclip test step by step, and what to do based on the result.

Answer:

Before you start — safety basics

• Unplug PSU from wall before doing any wiring/shorting. Only flip the switch ON after the paperclip is already inserted and PSU is plugged back in.
• Disconnect the PSU from everything else first: motherboard 24-pin, CPU 4/8-pin, all SATA/PCIe power cables, GPU power. The PSU should be a standalone unit, connected to nothing.
• Do this test on a non-conductive surface (not on a metal case panel).

Step-by-step

1. Fully disconnect the PSU from the case/motherboard. Pull it out if easy, or at minimum unplug the 24-pin ATX connector and every other cable from motherboard/GPU/drives. The PSU should have no load connected.

2. Locate the 24-pin ATX connector (the big one, the main motherboard power cable). Look at the plastic connector housing — pins are numbered, usually printed in tiny text on the plastic, or you can look up the pinout for your PSU brand.

3. Identify two wires:
   • Green wire = PS_ON# signal (pin 15 or 16 depending on 20 vs 24-pin layout)
   • Any black wire = Ground (there are several, any one works)
4. Bridge them:
   • Take a straightened paperclip (or a jumper wire, safer/more controlled)
   • Insert one end into the cavity holding the green wire pin, the other end into a cavity holding a black wire pin, on the connector face (not by piercing the wire insulation — insert into the connector housing itself where the pin socket is)
   • Make sure the two ends of the paperclip don’t touch anything else metal
5. Power on:
   • Plug the PSU’s power cable into the wall
   • Flip the PSU’s rear power switch to ON (I position)
   • The fan should spin up immediately if the PSU is functional
6. Observe carefully:
   • Listen — does the buzzing/whining happen again?
   • Watch the fan — steady spin, no stutter?
   • Smell — any burning smell? (If yes, power off immediately, unplug, stop testing)
   • Feel — is it noticeably hot within the first 10-15 seconds? (Should not be, no load is applied)
7. Power off:
   • Flip switch OFF, unplug from wall, remove paperclip

Interpreting the result

Result	Meaning	Next step
Fan spins clean, no buzz, no smell	PSU itself is likely healthy standalone	The buzzing you heard before was probably under load from motherboard/GPU — could be coil whine from GPU/VRM, or the PSU struggling under real load (which this test won’t reveal since there’s no load). Don’t rule out PSU yet — see load test below.
Buzzing/whining happens even standalone, no load	PSU internal fault (capacitor, transformer coil, switching regulator)	Stop testing repeatedly. Replace the PSU — it’s cheap (200-300 CNY) and physically easy: 4 screws mounting it to the case, then unplug/replug all connectors. No soldering needed.
Burning smell, smoke, or PSU doesn’t power on at all	Dead/dangerous PSU	Stop immediately, don’t reuse it, dispose of it, buy new PSU

If standalone test is clean but you want to isolate load-related buzzing:

Do a minimal load test instead of full rebuild:

• Reconnect only: 24-pin to motherboard + CPU power connector + nothing else (no GPU, no drives, no RAM even if possible, or minimal RAM)
• Power on via the case’s power button (not paperclip this time)
• If buzzing appears now but not in the fully standalone test → likely coil whine from motherboard VRMs or it’s a genuine PSU-under-load issue, not resolvable by just isolating PSU
• If it’s still silent → add components back one at a time (GPU next) until buzzing reappears — that tells you which component is drawing the noisy load

Bottom line decision tree for you right now:

1. Standalone paperclip test → 5 min, zero risk
2. Buzzes standalone → swap PSU yourself, done, cheap, low skill required
3. Silent standalone → do minimal-load test with just CPU+mobo → isolates whether it’s PSU-under-load or a downstream component
4. If after 2 tests you still can’t pin it down → that’s the point to hand it to the shop, because now diagnosis requires equipment (multimeter, load tester) you probably don’t have, and further blind trial-and-error risks the expensive parts (GPU, motherboard)

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