Tech & PC
How many watts does your PC power supply need?
How many watts your power supply needs based on GPU and CPU, with headroom and recommended standard sizes.
Quick answer
The power supply is the least glamorous part of a PC build and the worst one to get wrong: a failing cheap unit can take the motherboard and GPU down with it. Sizing is mostly about the graphics card — a modern GPU draws 3-8× more power than everything else combined — plus the CPU and about 75 W for motherboard, RAM, drives and fans.
Recommended PSU
650 W
- Estimated peak load
- 450 W
- Safety margin used
- ~40% headroom for spikes and efficiency
Includes ~75 W for motherboard, RAM, drives and fans. Modern GPUs have short power spikes above their rating, and a PSU running at 50-60% load is quieter and more efficient — that’s why the recommendation is not just the sum. Choose an 80 Plus Gold unit from a reputable brand; for RTX 50 cards prefer ATX 3.1 with the 12V-2x6 connector.
How it works
The number on the box is not the number to match to your components. Modern GPUs produce brief power spikes 1.5-2× above their average draw, and a PSU running around 50-60% load is quieter, cooler and at its peak efficiency. That’s why the calculator adds roughly 40% headroom to your estimated load before rounding up to a standard size. One more tip: spend on quality, not just watts — an 80 Plus Gold unit from a reputable brand at 750 W beats a no-name 1000 W every time.
Frequently asked questions
Is 750 W enough for an RTX 5070 build?+
Yes, comfortably. An RTX 5070 (~250 W) with a typical 8-core CPU lands around 450 W of peak load, so a quality 750 W unit leaves plenty of headroom. 650 W also works with an efficient CPU, but 750 W is the safer pick if you might upgrade the GPU later.
What does 80 Plus Bronze / Gold / Platinum mean?+
It’s an efficiency certification: how much wall power actually reaches your components instead of becoming heat. Bronze is ~85% efficient at half load, Gold ~90%, Platinum ~92%. Gold is the sweet spot for most builds — the extra cost pays back in lower heat and noise. The rating says nothing about build quality directly, but reputable brands rarely certify junk.
Do I need an ATX 3.1 PSU for RTX 50 series cards?+
Not strictly — adapters exist — but it’s strongly recommended. ATX 3.1 units have the native 12V-2x6 connector (the revised, safer version of the 12VHPWR that made headlines for melting) and are designed to tolerate the power spikes of modern GPUs. If you’re buying a new PSU today for a mid-range or better card, get ATX 3.1.
Can a PSU be too powerful for my PC?+
No — the PC only draws what it needs. A 1000 W unit powering a 400 W system is perfectly safe, just unnecessary money. The only real downside is efficiency: below ~20% load, efficiency drops a little. So oversizing by one step is smart future-proofing; oversizing by three steps is wasted budget that could have gone into the GPU.
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