Last verified 2026-09-13 by ReviewGamers Editorial
The power supply is the component people spend least time on and the one most capable of taking everything else with it. It is also the component where the headline number is least informative.
Wattage is a ceiling, not a description
A wattage figure tells you the claimed maximum continuous output. It tells you nothing about how stable that output is, how it behaves under sudden load, or how long it will hold up.
Two supplies with the same wattage on the box can differ enormously in build quality, protection features and real-world behaviour. This is why wattage alone is a poor buying criterion.
Transient load: the thing that actually catches people
Modern graphics cards do not draw a steady amount of power. They spike — briefly and sharply — well above their nominal draw.
A supply sized only for the average load can be tripped by those spikes, and the symptom is not a gradual decline. It is the system shutting off abruptly under load, usually in a demanding game, usually intermittently.
That failure is commonly misdiagnosed as a graphics card fault, a driver problem, or overheating. It is the supply hitting its protection limit.
Practical implication: headroom is not waste. A supply comfortably above your calculated draw absorbs spikes rather than tripping on them.
Efficiency ratings: useful, but not what people think
Efficiency certification describes how efficiently the supply converts mains power at given loads. A higher rating means less waste heat and slightly lower running cost.
It does not directly describe build quality, component grade, or reliability — although in practice higher-certified units are often better built, because manufacturers rarely pair good conversion with poor everything else.
Treat the rating as a useful correlation, not a guarantee.
Connectors: physically fitting is not the same as adequate
Connector standards for modern graphics cards have changed, and adapters exist. A connector that physically fits is not automatically delivering power the way the card expects.
Before a GPU upgrade, check the connector requirement specifically, not just the wattage. This is a common and expensive oversight, and adapter quality varies.
How to size it, practically
- Add up sustained draw for your CPU and GPU at their rated figures, plus a modest allowance for everything else.
- Add meaningful headroom for transient spikes and future upgrades.
- Check connector requirements for the specific card.
- Check physical dimensions against your case, especially in compact builds.
- Buy from a manufacturer with a real warranty and a track record.
The one component worth over-buying
This is not a general principle — we usually argue against paying for headroom you will not use. The power supply is the exception, for three reasons:
Failure is not contained. A poor supply failing badly can damage components attached to it.
It outlasts everything else. A good supply survives multiple builds. Amortised over eight years, the premium is small.
The failure mode is confusing. Intermittent shutdowns waste hours of diagnosis and frequently lead people to replace the wrong part first.
Buying in Australia
This is the clearest case in a PC build for buying locally from an accountable retailer.
A power supply is mains-connected equipment, and an unapproved or unaccountable import is a safety question before it is a warranty question. Under the Australian Consumer Law, goods must be of acceptable quality and durable for a reasonable period given the price, and your claim is against the retailer — which is practical locally and close to useless against an offshore seller.
If a failing supply damages other components, the difference between a local claim and an offshore one becomes very large very quickly.
This is general information, not legal advice.
What we have not measured
We have not tested any power supply. Ripple, transient response, protection behaviour and sustained output under thermal load require specialist equipment and units in hand.
This page explains what governs the decision. It does not recommend a model, because we have measured none of them.
