PSU Calculator
Estimate your PC's peak power draw and the PSU size to buy, with official board power and PSU minimums for GeForce RTX 50/40 and Radeon RX 9000/7000 cards.
Card power and PSU minimums are the makers' published figures (NVIDIA, AMD; checked November 2026). Factory-overclocked cards can draw more — check the card's own spec sheet.
High-power cards cause brief power spikes; an ATX 3.x power supply with a native 12V-2x6 (12VHPWR) cable is designed to ride through them.
| Component | Quantity | Watts each | Total W |
|---|---|---|---|
| Graphics card: GeForce RTX 5070 | 1 | 250 | 250 |
| Processor | 1 | 162 | 162 |
| Motherboard and chipset | 1 | 40 | 40 |
| Memory sticks | 2 | 5 | 10 |
| SSDs | 1 | 7 | 7 |
| Fans | 4 | 3 | 12 |
| RGB lighting | 1 | 5 | 5 |
| USB devices | 1 | 5 | 5 |
| Total peak load | 491 |
A power supply should cover the moment when the graphics card and processor both run flat out, with room to spare. This PSU calculator adds up the peak draw of each part — official board power for current GeForce and Radeon cards, real turbo power for popular CPUs — then picks a standard PSU size that keeps that peak at a sensible share of its rating, and shows the minimum PSU the card maker asks for.
How to use this tool
- Choose your graphics card (or enter another card's board power) and how many you run.
- Choose your processor by its peak package power, or type its PPT / PL2 figure.
- Adjust memory, drives, fans, pump, lighting and USB if your build differs.
- Pick how much headroom you want and read the recommended PSU size.
Formula
peak load = Σ (count × watts) × (1 + overclock %) · PSU ≥ peak load ÷ target load, rounded up to a standard size, and never below the GPU maker's minimum
Processor power uses AMD's package power tracking (PPT, 1.35 × TDP on AM4/AM5) or Intel's maximum turbo power (PL2), because the advertised TDP is lower than what the chip draws under full load. Standard sizes are 450, 550, 650, 750, 850, 1000, 1200, 1300, 1500 and 1600 W.
Example
A 285 W graphics card, a 125 W processor, 2 memory sticks at 5 W, 2 SSDs at 7 W and 4 fans at 3 W add up to 446 W at peak. Keeping that at 70% of the rating needs 446 ÷ 0.7 = 637 W, so the recommendation is a 650 W PSU. With an RTX 4060 and a Ryzen 7600-class chip the estimate is only 282 W, but NVIDIA lists 550 W required system power, so the tool suggests 550 W.
Frequently asked questions
Why aim for 60–80% load?
PSUs are most efficient around half to three-quarters of their rating, run their fans slower there, and keep a margin for ageing and for brief power spikes from modern graphics cards.
Does a bigger PSU waste electricity?
Not much. A PC only draws what it uses; an oversized unit is slightly less efficient at very low loads, but a good 80 PLUS Gold unit stays near 87–90% efficient across most of its range.
Why is the card maker's figure higher than my estimate?
NVIDIA and AMD size their minimums for a full system with a fast CPU and allow for lower-quality supplies. Following them is the safe choice, especially with a factory-overclocked card.
What about power spikes?
High-end cards can exceed their rated power for milliseconds. ATX 3.x supplies are built to tolerate these excursions; older units may shut down, which is another reason to keep headroom.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/psu-wattage-tool/
Cite or embed this tool
kakaoCalc. (2026, November 8). PSU Calculator. https://kakao.mobile/tools/psu-wattage-tool/
“PSU Calculator.” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/psu-wattage-tool/.
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