Use an online calculator (OuterVision expert mode) + add 100–150W for modern GPUs or future upgrades. Then cross-check with the GPU+CPU rule. If they differ by more than 150W, trust the higher value.
Fast, free, good for beginners. Cons: Inconsistent results across calculators (some overestimate by 100W+, others underestimate). OuterVision’s “Expert” mode is decent; basic mode often overshoots. 3. GPU + CPU Rule of Thumb (Quick Approximation) Formula: [ \textPSU Wattage = (\textGPU Max Power + \textCPU Max Power) \times 1.5 ] Then round up to the nearest 50W. how to calculate psu wattage
RTX 3080 (320W) + Ryzen 9 5900X (140W) = 460W × 1.5 = 690W → recommend 750W. Use an online calculator (OuterVision expert mode) +
Would you like a simplified checklist to calculate wattage for your specific build? trust the higher value. Fast
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