Is 650W enough for an RX 7800 XT + Ryzen 5 7600? (measured, not TDP)

Yes — 650 W handles this combination with room to spare.

noteSustained load: 401 W (Ryzen 5 7600 76 W measured peak + Radeon RX 7800 XT 250 W measured gaming + 75 W rest of system) = 62% of a 650 W unit.
goodSustained load is 62% of the unit's rating, and even the worst measured spike total (476 W) stays under 650 W.
noteSpike check: 76 W CPU + 325 W GPU spike + 75 W = 476 W momentary worst case — within the unit's rating.

The math, with sources

GPU sustained draw: 250 W — Radeon RX 7800 XT measured while gaming (TechPowerUp — GeForce RTX 5050 review, Power Consumption charts (July 2025 test suite)) — its rated board power is 263 W.
GPU transient spikes: 325 W — Radeon RX 7800 XT spikes to ~325 W for milliseconds (TechPowerUp — GeForce RTX 5050 review, Power Consumption charts (July 2025 test suite)). Spikes trip older PSUs that averages never show.
CPU peak draw: 76 W — Ryzen 5 7600 measured under heavy all-core load (TechPowerUp — Ryzen 5 9600X review, multi-threaded power chart (Blender, CPU-only)). Games draw less, but renders, encodes and shader compiles hit this.
Rest of the system: 75 W — Motherboard, RAM, drives, fans and USB devices — a fixed allowance.
Sustained total: 401 W — 76 + 250 + 75 = 401 W of steady load.
With 15% headroom: 461 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: 476 W — CPU peak + GPU spike + rest = 476 W for milliseconds. The recommendation also covers this outright, so even a pre-ATX-3.0 unit is not spike-tripped.
Recommended: 550 W — The smallest standard size covering both 461 W (sustained + headroom) and 476 W (spike total).

AFFILIATE_SLOT: tested 550W ATX 3.x unit picks will be listed here. No links yet — added only once real recommendations exist.