Power Supply Guide: How Many Watts Do You Really Need?

The PSU is the least glamorous part of a PC and the one you should never cheap out on. Here is how to size and choose it.

Why the PSU matters more than you think

The power supply feeds clean, stable electricity to every component. A poor one can be unstable, inefficient and — in the worst case — take other parts with it when it fails. This is the one component where buying a reputable, well-reviewed unit genuinely protects your investment.

A good PSU also runs quietly and lasts across several builds.

Sizing the wattage

Add up the power draw of your components — the graphics card and CPU dominate — and leave comfortable headroom, typically aiming for a unit rated around 30 to 50 percent above your expected peak. That headroom keeps the PSU running in its most efficient, quiet range and leaves room for upgrades.

For a mainstream gaming PC, 650 to 850 watts is usually the sweet spot; only high-end multi-GPU or extreme systems need more.

Efficiency and modularity

Look for an 80 PLUS rating (Bronze, Gold and above) as a sign of efficiency — a more efficient unit wastes less power as heat and costs less to run. A modular design lets you attach only the cables you need, which tidies the build and improves airflow.

Check that it has the right connectors for your graphics card, including the newer 12V-2x6 connector if your GPU requires it.

The bottom line

Never pair expensive components with a bargain-bin PSU. Buy a reputable unit with sensible headroom, a Gold efficiency rating and the connectors your parts need — it is cheap insurance for everything else in the case.