PSU Headroom & Efficiency Planner

First, the calculator sums your inputs into a Base Load: CPU watts + GPU watts + Other system watts. It adds your selected upgrade headroom to compute the Recommended Minimum PSU. Then it applies the transient spike risk profile to estimate a Spike-Adjusted Peak Load and flags how close your peak is to the recommended PSU.

This tool treats your CPU/GPU wattage entries as approximate sustained draws (not exact silicon limits), so realistic inputs produce more realistic results. Transient spikes are modeled with a simple risk multiplier, not brand-specific electrical behavior, so “high/very high” is meant to represent builds that can cause sharper GPU/CPU surges. PSU efficiency is checked in a simplified way to keep the recommendation near typical “sweet spot” usage for your expected load.

Don’t leave “Other system power draw” at zero—fans, drives, RAM, USB devices, lighting, and pumps can add up quickly. If you enter GPU or CPU wattage that already reflects peak/overclock behavior, use a reasonable headroom target to avoid double-counting. If your inputs push the recommendation above ~2000W, the tool warns the values may be unrealistic or include data-center-class hardware.

If GPU power is set to 0W, spike-risk logic still runs, but the tool defaults to low transient concern unless your CPU wattage is very high. With very low headroom (20% or less), the calculator can still recommend—but only for tightly controlled builds or strict budget scenarios. If the computed PSU wattage doesn’t land on a common PSU tier, it rounds up to the next standard tier (e.g., 450W, 550W, 650W, 750W, 850W, 1000W, 1200W, 1300W).