How to Tell If Your PSU Is Failing

Why PSU failures matter more than other component failures

A failing GPU stops working. A failing RAM stick causes crashes. A failing PSU can destroy everything connected to it.

Power supply failures range from gradual degradation — where the PSU quietly delivers less stable power over time — to catastrophic failure where voltage spikes fry the motherboard, GPU, CPU, and storage simultaneously. This is rare but it happens, and it’s why a failing PSU deserves more urgency than most other hardware problems.

The good news: PSUs usually give warning signs before they fail completely. Knowing what to look for lets you replace it before it takes anything else with it.

Warning signs of a failing PSU

Random crashes and blue screens of death

The most common symptom of PSU problems is system instability — random crashes, BSODs, or sudden shutdowns that don’t correlate with any specific software or game. The system was working fine, then it started crashing randomly, and no software fix helps.

Why PSUs cause this: As a PSU degrades, its voltage output becomes less stable. Components like the CPU and GPU are extremely sensitive to voltage fluctuations. When they don’t receive clean, stable power, they crash — and because the voltage issue is intermittent, the crashes seem random and unrelated.

How to distinguish PSU crashes from other causes:

• Crashes happen across multiple games and applications, not just one
• Crashes happen under load — when gaming, rendering, or running benchmarks
• BSODs show different error codes each time (hardware-related codes like WHEA_UNCORRECTABLE_ERROR, KERNEL_POWER, or CRITICAL_PROCESS_DIED)
• No software changes preceded the problem starting
• The system has been running fine for 2–3+ years

System won’t turn on, or turns off immediately

If your PC powers on for a fraction of a second then immediately shuts off, or won’t turn on at all despite power being connected, the PSU is a primary suspect.

A PSU with a failing protection circuit will attempt to start, detect an anomaly in its own output, and shut down immediately as a self-protection measure. This can look identical to a dead motherboard or CPU from the outside.

Test by swapping in a known-good PSU if one is available. If the system boots with a different PSU, yours is the problem.

Coil whine or unusual noises

Some coil whine from a PSU is normal — a faint high-pitched whine under load is common and not a sign of failure. What isn’t normal:

Loud buzzing or humming — indicates a failing capacitor inside the PSU. This will get worse over time and often precedes failure.

Clicking sounds — a clicking PSU is a serious warning sign. Power off and replace it.

Fan grinding or rattling — the PSU fan may be failing. A PSU with a dead internal fan will overheat and fail. Some PSUs have semi-passive fan modes that only spin the fan under load — make sure the fan actually spins when the system is under stress.

Burning smell — shut down immediately. Do not power back on until you’ve replaced the PSU.

Unstable voltages

The most direct way to assess PSU health is to monitor the voltages it’s actually delivering. A healthy PSU delivers stable voltages within a few percent of their rated values. A failing PSU delivers voltages that fluctuate or fall outside acceptable ranges.

How to check voltages:

HWiNFO64 (free): Download and run HWiNFO64 in sensors mode. Look for the +12V, +5V, and +3.3V rails. The 12V rail is the most important — it powers your CPU and GPU.

Acceptable voltage ranges:

Voltages consistently outside these ranges indicate a failing PSU. Voltages that fluctuate significantly under load — dropping when you start gaming or running a benchmark — indicate a PSU that can’t handle the current demand.

Important caveat: Motherboard voltage readings are not perfectly accurate. They’re indicative, not precise. A reading slightly outside range isn’t necessarily cause for alarm — a reading significantly or consistently outside range is.

System crashes specifically under load

If your PC is stable at idle or light use but crashes when gaming, running benchmarks, or doing anything demanding, the PSU is struggling to deliver adequate power under load.

This is different from crashes at any time — load-specific crashes point specifically to power delivery problems. The PSU can handle baseline power draw but can’t sustain the peak draw required during intensive workloads.

How to test this: Run a stress test like Prime95 (CPU) or Furmark (GPU) and monitor stability. If the system crashes within minutes under full load but is stable at idle, power delivery is suspect.

Age

PSUs degrade over time. Capacitors — the components responsible for smoothing and stabilizing voltage output — have a finite lifespan. A quality PSU from a reputable brand should last 7–10 years under normal use. Budget PSUs from unknown brands may start degrading in 3–5 years.

If your PSU is more than 5 years old and you’re experiencing any instability, replace it proactively. The cost of a new PSU is a fraction of the cost of replacing components damaged by a PSU failure.

How to test your PSU

The paperclip test (basic)

This tests whether the PSU can power on at all — it doesn’t assess voltage stability or capacity.

1. Power off and unplug the PSU from all components
2. Locate the 24-pin motherboard connector
3. Bend a paperclip into a U shape
4. Insert one end into the green wire pin (PS_ON) and the other end into any adjacent black wire pin (ground)
5. Plug the PSU into the wall and switch it on

If the PSU fan spins, the PSU can power on. If it doesn’t spin, the PSU is dead.

This test only confirms the PSU can start — it tells you nothing about whether it delivers stable voltages under load.

HWiNFO64 voltage monitoring under load (better)

1. Download and install HWiNFO64 (free)
2. Run it in sensors mode
3. Note the +12V, +5V, and +3.3V readings at idle
4. Run a demanding game or benchmark for 15–20 minutes
5. Monitor voltages under load — they should remain stable and within the acceptable ranges above

Voltages that drop significantly under load indicate the PSU can’t sustain output at your system’s power draw.

PSU tester (most reliable without a multimeter)

Dedicated PSU testers cost $15–$25 and give you a basic readout of each voltage rail without needing to run the full system. They’re more accurate than motherboard sensor readings. If you’re regularly building PCs or troubleshooting systems, one is worth having.

Swap test (most definitive)

If you have access to a known-good PSU of adequate wattage, swap it in. If the system’s problems disappear, your PSU was the cause. This is the most reliable test available — more reliable than any monitoring tool.

When to replace your PSU immediately

Replace your PSU without waiting if any of these are true:

• You smell burning from the PSU
• You hear clicking from the PSU
• The PSU has visible burn marks or damage
• The system crashes immediately on startup and a swap test confirms the PSU
• Voltages are significantly outside acceptable ranges under load
• The PSU is 7+ years old and you’re experiencing any instability

Don’t gamble on a PSU you suspect is failing. The replacement cost is always less than the potential damage.

What to replace it with

Wattage: Calculate your system’s power draw using PCPartPicker’s power estimator, then add 20–30% headroom. A system with a Ryzen 5 5600 and Arc B580 draws around 300W under full load — a 550W PSU gives comfortable headroom. A system with a Ryzen 7 9800X3D and RTX 5070 draws around 450W — an 850W PSU is appropriate.

Efficiency rating: 80 Plus Bronze is the minimum worth buying. Gold is worth the small premium for better efficiency and typically better build quality. Avoid unrated PSUs entirely.

Brand: Corsair, Seasonic, be quiet!, and EVGA (older units) have strong reliability track records. Avoid no-name brands regardless of price — a cheap PSU is a false economy when it can destroy your entire build.

Modularity: Fully modular PSUs let you connect only the cables you need, which simplifies cable management significantly. Worth the small premium especially in smaller cases.

Our current recommendation for most builds is the Corsair RM850x — reliable, fully modular, 80 Plus Gold, and enough headroom for a future GPU upgrade.

The warning signs checklist

• Random crashes or BSODs across multiple applications
• System shuts off under load but stable at idle
• Clicking, buzzing, or burning smell from PSU
• +12V rail dropping below 11.4V under load in HWiNFO64
• PSU is 5+ years old with any instability present
• System powers on for a second then immediately shuts off
• Crashes started gradually and have gotten worse over time

If two or more of these apply, replace the PSU before it takes anything else with it.

Dealing with other hardware problems? See our PC won’t POST guide, no display guide, or stuttering guide for more troubleshooting help.