The power supply (PSU) is the part nobody sees and the one most often chosen as an afterthought. Yet it feeds every component, and a poor one can cause crashes, noise or, in rare cases, damage. Choosing a good one is not complicated.
How many watts?
Add up the power your graphics card and processor draw, then leave headroom for the rest of the system and for power spikes. The simplest method is to use your graphics card maker’s recommended PSU wattage, which already accounts for a typical system, or a calculator such as the one on PCPartPicker or the OuterVision PSU calculator.
As a rough guide, a mid-range gaming PC is comfortable on 650 to 750 W, and high-end systems with powerful graphics cards need 850 W or more. A PSU working at around half to two-thirds of its capacity is efficient and quiet.
Quality before wattage
A good 650 W unit is better than a poor 850 W one. Signs of quality:
- A reputable brand and, ideally, independent reviews of that specific model (Cybenetics and specialist reviewers test them under load).
- An 80 Plus efficiency rating; Bronze is acceptable, Gold is the common choice for gaming PCs.
- Full protections: over-current, over-voltage, short-circuit and over-temperature.
- A long warranty, often 7 to 10 years on good units.
Connectors and ATX 3.x
Recent high-end graphics cards from NVIDIA use the 12V-2×6 connector (the updated version of 12VHPWR). An ATX 3.0 or 3.1 power supply has a native cable for it and is designed to handle the short power spikes modern cards produce. With an older PSU, you need an adapter, which works but is less tidy. Whatever the connector, push it in fully: a partly inserted plug is the main cause of the melted-connector reports seen with these cards.
Modular or not?
Fully modular power supplies let you connect only the cables you need, making a cleaner and better-ventilated build. Semi-modular units are a good compromise. Non-modular units work fine but leave unused cables to hide.
Signs of a failing PSU
Random shutdowns under load, reboots when a game starts, a burning smell or loud buzzing are warning signs. Stop using the PC and test with a known-good unit. Never open a power supply: its capacitors can hold a dangerous charge even when unplugged.
