Pick your CPU, graphics card and the rest of your parts below, and the calculator estimates how much power your gaming PC draws under load, the PSU size to buy, and the cables your power supply needs. It covers current Ryzen 9000 and Core Ultra chips, Intel 14th gen, and the RTX 50, RTX 40, Radeon RX 9000/7000 and Arc B580 cards most people are building with in 2026.
PSU wattage calculator
PSU checklist
Why this number
| Part | Watts | How it is counted |
|---|
Estimates, not measurements. Figures use manufacturer power ratings (TDP/PPT, PL2, total graphics power) plus typical draws for other parts. Factory-overclocked graphics cards can draw 5-15% more than the reference rating, so check your exact card's spec page too.
How the estimate works
The calculator adds up a worst-case sustained load: the moment when both the CPU and the graphics card run at full power, such as a demanding game while you stream, or a stress test.
- CPU. We use the stock power limit, not the TDP printed on the box. For Ryzen that is PPT (88 W for a Ryzen 7 9700X, 162 W for a 9800X3D, 230 W for a 9950X). For Intel it is Maximum Turbo Power, or PL2 (159 W for a Core Ultra 5 245K, 250 W for a 285K, 253 W for an i9-14900K). In most games a CPU draws well below this, which is why the tool also shows a typical gaming figure.
- Graphics card. The rated total graphics power (NVIDIA) or typical board power (AMD, Intel): 575 W for an RTX 5090, 250 W for an RTX 5070, 304 W for an RX 9070 XT.
- Everything else. About 45 W for the motherboard and USB, plus small allowances for each RAM stick, drive, fan, AIO pump and RGB.
- Overclocking. Light tuning (Precision Boost Overdrive, a raised power slider) adds about 10% to the CPU and 7% to the GPU. Heavy tuning with unlocked limits adds 30% and 15%.
The total is then divided by 0.85, so the power supply never runs above about 85% of its rating, and rounded up to the next common size: 550, 650, 750, 850, 1000, 1200 or 1600 W. A PSU at 50-85% load runs cooler and quieter, sits in its best efficiency range, and still has margin after a few years of capacitor aging.
Transient spikes and why ATX 3.1 matters
Modern graphics cards do not draw a smooth, flat load. When a scene changes, power can jump well above the rated figure for a few milliseconds. These transient spikes are too short to heat anything, but an older power supply can read them as a fault and shut the PC off mid-game, even when its average load is fine.
The ATX 3.0 and ATX 3.1 standards fixed this by writing spikes into the spec. A compliant unit must ride through 200% of its rated power for 100 microseconds and 180% for 1 millisecond, and the PCIe CEM 5.x rules allow a card to pull up to three times its sustained power through the 16-pin connector for 100 microseconds. ATX 3.1 also swapped the original 12VHPWR plug for 12V-2×6, which has longer power pins and shorter sense pins, so the card only draws full current when the plug is fully seated. NVIDIA recommends a PCIe CEM 5.1 compliant PSU for RTX 50 cards.
That is why the tool shows two sizes. The main figure assumes an ATX 3.1 (or 3.0) unit. If you are reusing an older ATX 2.x power supply, the second figure sizes up so it covers the spikes at 100% of its rating.
Why the GPU maker’s figure still matters
NVIDIA, AMD and Intel publish a recommended system power for every card: 650 W for an RTX 5070, 750 W for an RX 9070 XT, 1000 W for an RTX 5090. Those numbers are built on a high-end test system (NVIDIA uses a Ryzen 9 9950X) and allow for average-quality power supplies, so they are often higher than what a mid-range build needs. When the vendor figure is higher than our estimate, the tool flags it. Following it costs a little more but keeps you within the maker’s guidance if you ever need support, and leaves room for a faster CPU later.
Frequently Asked Questions
Is a 750 W PSU enough for an RTX 5070 Ti?
Yes for most builds. NVIDIA recommends 750 W, and a stock RTX 5070 Ti with a Ryzen 7 9800X3D comes out around 550 W sustained. With a 230-250 W CPU such as a Ryzen 9 9950X or Core Ultra 9 285K, 750 W still works, but 850 W gives more breathing room.
Do I need an ATX 3.1 power supply for an RTX 50 series card?
It is not strictly required, since the cards ship with an 8-pin adapter, but it is strongly recommended. An ATX 3.1 unit has a native 12V-2×6 cable and is tested to handle the short power spikes these cards produce.
Is a bigger PSU less efficient?
Only slightly at very low loads. A quality 850 W unit at idle wastes a few watts more than a 650 W unit, but under gaming load the difference is small. Buying one size up is fine; buying two or three sizes up mainly costs money.
Gold or Platinum efficiency?
80 Plus Gold is the sweet spot for most gaming PCs. Platinum makes sense around 850 W and up, or when the PC runs under heavy load for many hours a day, because it turns less power into heat and noise.
Can I use 8-pin to 16-pin adapters safely?
Yes, if you use the adapter that came with the card and plug each 8-pin end into its own PSU cable rather than one daisy-chained cable. Push the 16-pin plug in until it is fully flush, and avoid sharp bends right at the connector.
These results are estimates, not measurements. They are based on manufacturer power ratings and typical draws for other parts. Factory-overclocked cards and individual chips vary, so check your exact model’s specifications before you buy.