BuildPC

PSU Calculator

Total component load plus headroom — PSUs run most efficiently well under their max rating, not maxed out.

Why headroom matters

PSUs are most efficient (and quietest, and longest-lived) running at 50-80% of their rated capacity, not pegged at 100% — headroom also leaves room for future upgrades like a more powerful GPU.

GPU is usually the biggest factor

A modern high-end GPU alone can draw 300-450W under load — check your specific GPU and CPU's rated power draw (TDP) rather than guessing, since they vary enormously across different models.

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BuildPC

PSU Calculator

Total component load plus headroom — PSUs run most efficiently well under their max rating, not maxed out.

Total component wattage (W)

Safety headroom (%)

Recommended PSU (W)

455

Add up your GPU, CPU, and other components' rated wattage first — PSUs run most efficiently at 50-80% load, not maxed out.

What you entered

Total component wattage (W): 350Safety headroom (%): 30

1
Add 30% headroom for efficiency and future upgrades
350 × 1.30= 455 W

Result

Recommended PSU (W): 455

350W of components with 30% headroom calls for at least a 455W power supply.

Why headroom matters

PSUs are most efficient (and quietest, and longest-lived) running at 50-80% of their rated capacity, not pegged at 100% — headroom also leaves room for future upgrades like a more powerful GPU.

GPU is usually the biggest factor

A modern high-end GPU alone can draw 300-450W under load — check your specific GPU and CPU's rated power draw (TDP) rather than guessing, since they vary enormously across different models.