Is 550W enough for an RTX 4070 + Ryzen 5 5600?
Yes — 550 W handles this combination with room to spare.
- noteSustained load: 344 W (Ryzen 5 5600 76 W power-limit budget + GeForce RTX 4070 193 W measured gaming + 75 W rest of system) = 63% of a 550 W unit.
- goodSustained load is 63% of the unit's rating, and even the worst measured spike total (392 W) stays under 550 W.
- noteSpike check: 76 W CPU + 241 W GPU spike + 75 W = 392 W momentary worst case — within the unit's rating.
The math, with sources
- GPU sustained draw: 193 W — GeForce RTX 4070 measured while gaming (TechPowerUp — GeForce RTX 5050 review, Power Consumption charts (July 2025 test suite)) — its rated board power is 200 W.
- GPU transient spikes: 241 W — GeForce RTX 4070 spikes to ~241 W for milliseconds (TechPowerUp — GeForce RTX 5050 review, Power Consumption charts (July 2025 test suite)). Spikes trip older PSUs that averages never show.
- CPU power budget: 76 W — Ryzen 5 5600 budgeted at its official turbo power limit (AMD spec sheet — official TDP + PPT socket power limit; budgeted at the PPT limit (no bench chart read for this part)). No bench chart was read for this part, so the calculator uses the vendor's own ceiling — the real peak sits at or below it.
- Rest of the system: 75 W — Motherboard, RAM, drives, fans and USB devices — a fixed allowance.
- Sustained total: 344 W — 76 + 193 + 75 = 344 W of steady load.
- With 15% headroom: 396 W — Sustained x 1.15 — margin for capacitor aging, heat, and staying near the efficiency sweet spot. (The sustained figure is already conservative: CPU all-core peak and GPU gaming peak rarely coincide.)
- Spike check: 392 W — CPU peak + GPU spike + rest = 392 W for milliseconds. The recommendation also covers this outright, so even a pre-ATX-3.0 unit is not spike-tripped.
- Recommended: 450 W — The smallest standard size covering both 396 W (sustained + headroom) and 392 W (spike total).
Measured numbers from
- GeForce RTX 4070: TechPowerUp — GeForce RTX 5050 review, Power Consumption charts (July 2025 test suite)
- Ryzen 5 5600: AMD spec sheet — official TDP + PPT socket power limit; budgeted at the PPT limit (no bench chart read for this part) (no stable link)
AFFILIATE_SLOT: tested 450W ATX 3.x unit picks will be listed here. No links yet — added only once real recommendations exist.