Power Supply Wattage for a Gaming PC: How to Pick the Right Size

The power supply is the part of a gaming PC that people choose last and regret first. Too weak, and the PC can shut down in the middle of a match. Too big, and you pay for capacity you will never use. This guide shows how to read the numbers the graphics card makers publish, how to add a sensible margin, and what to check besides the watts.

What the power supply does

The power supply unit, or PSU, turns the power from your wall socket into the lower voltages that the parts inside the PC use. Its wattage rating is the most power it can deliver. Your PC does not draw that much all the time. At the desktop it may use a small part of it, and in a demanding game the graphics card and the processor use the most.

Start with the graphics card

The graphics card is usually the biggest consumer. Card makers publish two useful numbers: how much power the card itself uses, and the minimum power supply they recommend for the whole PC.

• NVIDIA's page for the GeForce RTX 5070 family lists a total graphics power of 250 W for the RTX 5070 and 300 W for the RTX 5070 Ti. It lists a required system power of 650 W and 750 W for the two cards.
• AMD's page for the Radeon RX 9070 XT lists a typical board power of 304 W for desktop and a minimum PSU recommendation of 750 W.

NVIDIA adds two notes. The system power figure is based on a PC with a Ryzen 9 9950X processor, and requirements can be different depending on the configuration. The numbers are for the reference design, and cards from other brands can have different specs. So read the page of the exact model you plan to buy.

Why the recommended number is bigger than the card's power

The recommendation covers the whole PC, not just the card. The processor, the memory, drives, fans and USB devices all draw power, and the supply needs room for spikes. That is why a 300 W card comes with a 750 W recommendation. Following the maker's number is the simplest safe choice. Going a little higher gives extra headroom, but you do not need to double it.

A simple way to choose

1. Find the card's recommendation. Look at the maker's specification page for your model.
2. Check your processor. If you use a high-end processor that draws a lot of power, or you plan to overclock, pick the next size up.
3. Add headroom. A supply that works at a moderate load is usually quieter and runs cooler. Choosing the next common size above the recommendation is a reasonable margin, for example 850 W instead of 750 W.
4. Think about upgrades. If you will probably buy a stronger card in a year or two, a slightly bigger supply now can save you from buying twice.

Check the connectors, not only the watts

The power connectors matter as much as the number. The NVIDIA page lists two PCIe 8-pin cables, with an adapter in the box, or a PCIe Gen 5 cable rated 300 W or more for the RTX 5070 and RTX 5070 Ti. Before you buy, look at the supply's cable list and count how many separate PCIe cables it has. Use the cables that came with that supply, and do not mix cables between different models.

Quality counts too

Two supplies with the same wattage can be very different. Look for a known brand, a clear warranty and independent reviews. An efficiency rating such as 80 Plus tells you how much power is lost as heat, not how good the supply is overall. A cheap supply from an unknown seller is a risky place to save money, because a failure can damage other parts.

Common mistakes

• Buying by wattage alone and ignoring the connectors.
• Using an old supply that is many years old with a new, power-hungry card.
• Choosing a huge supply for a small PC, which costs more and gains nothing.
• Reusing cables from a different supply.

Checklist

• Read the power page of your exact graphics card.
• Compare the recommendation with your processor and plans.
• Add a margin of one size.
• Count the PCIe cables and check the connectors.
• Pick a known brand with a solid warranty.

If your PC already shuts down or restarts under load, check temperatures first with our guide on what CPU and GPU temperatures are normal. For the rest of the build, see how much video memory you need and SSD or HDD for games.