What power supply wattage do I need?

A PC that restarts mid-game with no error message and no obvious heat problem is usually a power supply tripping on a spike it couldn't handle.

Most gaming PCs need between 550W and 850W and only builds with the very top graphics cards need to go beyond that. The graphics card makes up most of the required wattage, and graphics card manufacturers publish a recommended figure for each one. Those recommendations already assume a power-hungry processor alongside the card and already include headroom, so for a normal single-card build the recommended number is the number to buy rather than a floor to double.

Here's what that looks like for current NVIDIA cards, using the figures NVIDIA publishes.

AMD's cards sit at similar points for similar performance. If you're specifying a build, find your card's recommended figure and start there.

A few situations justify going above the recommended wattage.

Processors that draw a lot of power under load, which mostly means the higher-power Intel chips rather than AMD's current range, adds meaningfully to the total.

A factory-overclocked version of a card pulls more than the reference figure the recommendation is based on.

And if you expect to upgrade the graphics card within a couple of years, buying a bigger power supply now saves replacing the power supply later. That's a reasonable argument, unlike the general future-proofing one below.

Buying a 1000W unit for a 5070 build isn't future-proofing, it's paying for capacity you'll never use.

Power supplies are at their most efficient somewhere between 40% - 80% load; technically 60%-80% is more efficient than 40% - 50% but it’s by 1% or 2%. Therefore, a 1000W unit running a build that draws 380W sits at under 40%, which is okay to run at but it is inefficient and you've spent extra for it.

More importantly, wattage isn't the same as quality. A cheap 1000W unit is a worse purchase than a good 750W one, because what fails in a bad power supply isn't capacity, it's the ability to hold voltage steady when demand changes suddenly.

Modern graphics cards don't draw power smoothly: they spike.

A card rated at 575W can briefly pull far more than that for a fraction of a millisecond, and independent testing found the RTX 5090 hitting around 901W in bursts of under a millisecond; averaged over a second, you would never see it. The power supply has to absorb it in real time, and a unit that can't will shut the system down.

This is what the ATX 3.1 and PCIe 5.1 standards address. Units built to them are specified to ride out those excursions, and they come with the native 12V-2x6 cable that current cards use rather than an adapter splitting several older connectors into one. For a build with a current graphics card, an ATX 3.1 unit at the recommended wattage is a better purchase than a much larger older one.

If you're reusing a power supply from a previous build, this is the thing to check before the wattage.

The 80 Plus badges, Bronze through Titanium, describe how much power is lost as heat converting mains electricity to what your components use.

The common misunderstanding is that a higher rating means your PC uses less power. It doesn't. Your components draw what they draw. A better rating means less waste on top of that, so slightly lower bills and less heat dumped into the case. Less heat also means the PSU, CPU cooler, and case fans will not have to spin as fast to cool the system, which means the system will be quieter.

Gold is the sensible default and where most quality units sit. Platinum and Titanium cost more for a small further gain, worth it if the machine runs long hours and not worth chasing for gaming. Below Bronze, be careful, because very cheap units often carry weak certification alongside everything else that's weak about them.

Use the cable the power supply came with, and for a high-draw card use the native 12V-2x6 connector rather than an adapter with several plugs feeding into it. Daisy-chaining one cable to serve two connectors on a demanding card is a common shortcut and a bad one.

The components inside PSUs degrade over years, so a unit that comfortably ran a build a decade ago isn't the one to put behind a new graphics card. If you're carrying a power supply forward into a new build, look at how old it is as well as what it's rated for. It's the one component where a failure could cause irreparable damage to other components.

If you want to sanity check a suggested wattage figure rather than trust a table, add the card's rated draw to the processor's, add somewhere around 100W for the board, drives, memory and fans, then add a margin of roughly a 1/3. You'll usually land close to the manufacturer's recommendation, which is a reasonable sign the recommendation is honest.

For most people that arrives at 650W or 750W, which is why those two sizes cover the majority of gaming builds.

Buy the wattage your graphics card manufacturer recommends. Buy an ATX 3.1 unit with a native 12V-2x6 cable. Choose 80 Plus Gold unless there's a reason not to. Don't buy an enormous unit as insurance, and don't reuse a very old one to save money on a build that costs 10 times what it would.

You can see what we stock in power supply units, and if you're specifying a full build the PC configurator matches the supply to the parts you pick. Complete systems from the gaming PC range ship with this already worked out.

What to read next 

• Gaming PC buying guide for the whole decision, not just the processorer.
• Motherboard buyer guide for chipsets and what each one gives you.
• GPU buyer guide for the component that sets your frame rate