Definition: A PSU (Power Supply Unit) converts mains AC power into the DC voltages that every component in a desktop PC requires. It is rated by wattage (total power it can deliver) and efficiency (80 Plus Bronze, Silver, Gold, Platinum, Titanium). An underpowered or failing PSU causes random shutdowns, crashes, and system instability.
Why it matters for desktop upgrades
The PSU is the component most commonly overlooked during desktop upgrades. Adding a new high-end GPU or CPU to a system with an ageing or undersized PSU often causes immediate instability. As a general rule: budget 50–100W of headroom above your calculated system TDP. An RTX 4090 system needs 850W minimum.
Signs your PSU needs replacing
- Random shutdowns or reboots under load (gaming, rendering)
- System stable at idle but crashes when GPU or CPU is stressed
- Coil whine increasing over time
- PSU fan stopped spinning or grinding noise from PSU
- Burning smell from the rear of the case
People Also Ask
How do I know if my PSU is failing? +
The clearest signs: random shutdowns or restarts under load (gaming, video encoding) that don’t happen at idle, system won’t POST after adding a new component, burning or electrical smell from the rear of the case, PSU fan making noise or not spinning, and coil whine that worsens over time. PSU failure is often misdiagnosed as a GPU or CPU fault. BreakFixNow diagnoses desktop power delivery issues as part of every free assessment.
What wattage PSU do I need in Singapore? +
Budget 50–100W above your calculated system TDP. Common reference points: office PC (no dedicated GPU) — 400W is plenty. Mid-range gaming rig (RTX 4060/4070 + Ryzen 5/7) — 650W 80+ Gold. High-end gaming rig (RTX 4080/4090) — 850W–1000W 80+ Gold or better. In Singapore, 80+ Gold is the recommended minimum for gaming rigs — higher efficiency means less waste heat inside the case, which matters in our warm climate.
Can a bad PSU damage other components? +
Yes — a failing PSU can deliver unregulated voltages that damage the motherboard, GPU, and CPU. This is why cheap PSUs from unknown brands are a false economy. A PSU failure that takes out the motherboard or GPU turns a $60 PSU replacement into a $400–$800 repair. Budget-brand PSUs also lack protections (OVP, OCP, SCP) that shut down safely instead of damaging other components when they fail.
How long does a PSU last? +
Quality PSUs from reputable brands (Seasonic, Corsair, be quiet!, EVGA) last 7–10 years under normal use. Budget PSUs from unknown brands may fail within 2–3 years. In Singapore’s warmer climate, PSUs in cases without good airflow run hotter, which accelerates capacitor degradation. If your system is more than 7 years old and starts showing instability under load, the PSU is worth inspecting even if it hasn’t failed outright.
What is 80 Plus Gold and why does it matter? +
80 Plus Gold means the PSU converts mains power at 87–90% efficiency — less than 10–13% is lost as heat. This matters for two reasons: less heat generated inside the case (important in Singapore’s ambient warmth) and lower electricity bills over time (relevant given Singapore’s electricity rates). Bronze-rated PSUs run at 82–85% efficiency. The price difference between Bronze and Gold is usually small and pays back over the PSU’s lifetime.
Related terms
- Motherboard — receives power from the PSU via 24-pin ATX connector
- GPU — the highest power draw component; size your PSU around it
System crashing under load?
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