Recommended PSU
550 W
DC Load
423 W
AC Draw
635 W
Recommended PSU
550 W
DC Load
423 W
With Headroom
508 W
AC Draw
635 W
Rails
2
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Inputs
Result
DC = 120+300+3.3 = 423.3W. With headroom: 423.3×1.2 = 508W. AC: 508/0.8 = 635W. Round up to 650W.
Inputs
Result
DC = 60+2.5+10.8 = 73.3W. With headroom: 73.3×1.2 = 88W. AC: 88/0.8 = 110W. Round up to 150W.
Add up watts for each component: W = V × I. Then add headroom (20%) and divide by PSU efficiency (80%). Example: 300W load × 1.2 headroom / 0.8 efficiency = 450W PSU.
| Component | Voltage | Current | Power |
|---|---|---|---|
| CPU | 12V | 10A | 120W |
| GPU | 12V | 25A | 300W |
| RAM (2x) | 3.3V | 0.5A | 3.3W |
| 5 Fans | 12V | 0.3A | 18W |
80 PLUS rated PSUs: White = 80%, Bronze = 82-85%, Gold = 87-90%, Platinum = 92-94%, Titanium = 96%. Higher efficiency wastes less power as heat.
20% headroom is standard for steady loads. For gaming PCs with GPU power spikes, use 25-30%. For servers with UPS, 40% headroom ensures startup current handling.
An oversized PSU works fine but wastes money. PSUs are most efficient at 40-60% load. A 1000W PSU at 200W load runs at lower efficiency than a 500W PSU at the same load.
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Last Updated: Mar 20, 2026
This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.