How the PSU calculator works
Each part is counted at its maximum power: the processor at its top boost power (not the lower "TDP" printed on the box), the graphics card at its total board power, plus about 50 W for the motherboard, 5 W per memory stick, 6 W per SSD, 9 W per hard drive and 3 W per fan. Then it adds 20% of the graphics card's power for short spikes and 10% overall headroom, and rounds up to a common power supply size.
Typical power supply sizes
| Build type | Example | Typical PSU |
|---|
| Office or home PC, no graphics card | Ryzen 5 / Core i5 with integrated graphics | 450 W |
| Entry gaming | Ryzen 5 + RTX 5060 / RX 7600 | 550 W |
| Mid-range gaming | Core i5 / Ryzen 7 + RTX 5070 / RX 9070 | 650–750 W |
| High-end gaming | Ryzen 7 X3D + RTX 5080 / RX 9070 XT | 850 W |
| Enthusiast | Core Ultra 9 / Ryzen 9 + RTX 5090 | 1000–1200 W |
Choosing a good power supply
- Buy from a reputable brand with a long warranty (7 to 12 years on good units).
- Look for 80 Plus Gold efficiency or better for gaming PCs.
- For new graphics cards, an ATX 3.1 unit with a native 12V-2x6 cable is the simplest choice.
- Check the graphics card maker's recommended PSU wattage too; it is usually a safe minimum.
Testing your new PC? Try the FPS test and the gamepad tester.
Last reviewed October 2026.
Frequently asked questions
How many watts does my PC need?
Add up the maximum power of every part. The graphics card and processor use most of it; the motherboard, memory, drives and fans add roughly 70 to 120 W more. This calculator adds those up and then adds headroom for power spikes and efficiency.
Why recommend more watts than my PC uses?
Modern graphics cards can briefly spike well above their rated power. A power supply with headroom handles those spikes without shutting down, runs cooler and quieter, and leaves room for a future upgrade. Power supplies are also most efficient at around 50% to 80% load.
Does a bigger power supply use more electricity?
No. A PC only draws the power it needs. A 1000 W unit powering a 400 W system uses about the same electricity as a 650 W unit, and can even be slightly more efficient. The main downsides of oversizing are cost and, at very low loads, slightly lower efficiency.
What do 80 Plus Bronze, Gold and Platinum mean?
They are efficiency ratings. A Gold unit wastes less power as heat than a Bronze one (around 90% vs 85% efficient at half load), so it runs cooler and costs a little less to run. Gold is a good balance for most gaming PCs.
Do I need a 12V-2x6 (12VHPWR) connector?
Many NVIDIA RTX 40 and 50 series cards use the 16-pin 12V-2x6 connector. An ATX 3.0 or 3.1 power supply with a native cable is the cleanest option; otherwise use the adapter that comes with the card and make sure it clicks fully into place.