How many watts does my gaming PC need?

How much wattage does my PC need?

The power supply (PSU) must deliver enough continuous wattage for every component at full load, plus margin. Almost all of a gaming PC's power goes to two parts: the graphics card and the CPU. Motherboard, RAM, drives, fans and USB devices add roughly 50–100 W in a typical build. This calculator uses the manufacturer's rated board power for GPUs and the maximum turbo/package power for CPUs, adds per-component estimates for the rest, and then applies about 30% headroom and rounds up to a standard PSU size.

Why add headroom?

Transient spikes: modern GPUs can briefly draw far more than their rated power for milliseconds. Cheaper or undersized PSUs may trip their protection and shut down the PC mid-game. Efficiency: PSUs are usually most efficient at around 40–60% load, so a unit that is not running at its limit is cooler and quieter. Ageing and upgrades: capacitors degrade slowly over years, and you may want a faster GPU later. Headroom covers all three without paying for a huge unit you don't need.

Quick reference by GPU

These assume a mid-range CPU. Pair a top GPU with a high-power CPU like a Core i9 and you should go one step higher. Always check the GPU maker's own recommended PSU size too; they tend to be conservative because they cannot know your exact build.

Watts are not everything: what else to check

Efficiency rating

80 Plus Bronze, Gold, Platinum and Titanium describe efficiency, not quality. Gold is the sweet spot for most gaming builds. A good Bronze unit is fine for budget PCs.

ATX 3.0 / 3.1 and 12V-2x6

Newer PSUs are designed to tolerate GPU power spikes and include the 12V-2x6 (successor to 12VHPWR) connector for recent high-end NVIDIA cards. It avoids adapters and is recommended for 300 W+ GPUs.

Brand and reviews

Two PSUs with the same wattage can be very different inside. Look for in-depth reviews and tier lists from independent testers, a long warranty (7–10 years on good units) and protections such as OCP, OVP, OPP, SCP and OTP.

Form factor and modularity

Small cases may need SFX or SFX-L units. Fully modular cables make building and airflow easier.

Common mistakes

• Buying a cheap no-name PSU to save money on a costly GPU.
• Trusting the wattage on the box of an unknown brand.
• Going massively oversized "just in case"; 1,200 W for an RTX 4060 build wastes money.
• Using daisy-chained PCIe cables on 300 W+ GPUs when the PSU maker advises separate cables.

Worked examples

Budget 1080p build: Ryzen 5 7600 (88 W) + RTX 4060 (115 W) + two RAM sticks, one SSD and three fans comes to about 290 W at peak. With headroom the calculator suggests a 450 W unit, but many builders pick a good 550 W model because it costs little more and leaves room for a GPU upgrade. High-end 1440p build: Core i7-14700K (253 W) + RTX 4070 Ti Super (285 W) reaches roughly 610 W, so 800–850 W is sensible. Enthusiast 4K build: Ryzen 7 9800X3D + RTX 5090 is around 820 W before headroom; a quality 1000–1200 W ATX 3.1 unit is the safe choice.

How to measure real power draw

Calculators estimate worst-case peaks. If you already own the PC, a plug-in wall power meter shows total draw from the socket, which includes PSU losses: a system drawing 400 W from the wall on a 90%-efficient PSU is delivering about 360 W to components. Software such as HWiNFO reports CPU package power and GPU board power. Run a demanding game and a stress test, note the highest figures, and compare them with your PSU rating. If you regularly see sustained draw above about 80% of the rating, consider a bigger unit.

Signs your power supply is not enough

• The PC shuts off or reboots during gaming but not on the desktop.
• GPU driver crashes or black screens under heavy load.
• Coil whine or a loud PSU fan at all times.
• Instability that disappears when you lower the GPU power limit.

These symptoms can also come from faulty RAM, drivers or overheating, so test methodically, but an old or undersized PSU is a common cause after a GPU upgrade.

Upgrading a prebuilt PC

Many prebuilt and office PCs ship with 300–500 W supplies, sometimes in proprietary sizes and with only one or no PCIe power cable. Before buying a new graphics card for one, check the PSU label for its wattage and 12 V rating, count the available PCIe connectors and measure the case. Swapping to a standard ATX unit is often possible but not always, so check the case and motherboard first.

Wattage figures are approximate manufacturer specs and real draw varies by workload and settings. Planning the rest of your build? See current GPU and PC prices on Gaming PC Price.

Frequently asked questions