A/B Testing PC Power Supply Calculator FAQ
Answers to common questions about comparing PC PSU wattage, headroom, component inputs, and load percentage per user.
Use these answers to understand what the A/B PC power supply calculator estimates, which power figures to enter, and what the results do not verify.
General calculator questions
What the A/B comparison is designed to show.
What does this A/B PC power supply calculator compare?
It compares estimated PSU capacity and selected PSU load for two separate PC configurations, labeled A and B.
What does per-user mean in this calculator?
Each result applies to one PC, user, or workstation. It is not a combined power calculation for multiple machines.
Can I use it for gaming PCs and workstations?
Yes. Enter realistic peak CPU, GPU, and other-component power estimates for each configuration.
Does the calculator measure actual power use?
No. It produces an estimate from the values entered rather than a live hardware measurement.
Inputs and component estimates
Choosing useful values for the calculation.
What CPU power figure should I enter?
Use a realistic peak or sustained package-power estimate. A CPU's advertised base power may be lower than its boost behavior.
What GPU power figure should I enter?
Use an expected peak board-power estimate for the graphics card, based on reliable specifications or detailed testing.
What belongs in other component power?
Include the motherboard, RAM, storage, fans, pumps, USB devices, and other internal components not already counted as CPU or GPU power.
Should I enter idle power?
No. This calculator is intended for peak-demand planning, not idle consumption.
Can I include overclocking or raised power limits?
Yes, if the entered CPU and GPU figures reflect the expected higher power demand.
Headroom and recommendation results
How capacity recommendations are formed.
What is PSU headroom?
It is extra capacity added above estimated component demand to allow for uncertainty, sustained load, upgrades, and power spikes.
How much headroom should I select?
The calculator lets you choose the margin. A larger margin creates a higher estimated recommendation, especially when input figures are uncertain.
Why is the result rounded to the next 50 W?
The calculation rounds upward in 50 W increments so the recommendation remains at or above the headroom-adjusted target.
What does the difference in recommended capacity mean?
It is the absolute difference between the rounded PSU recommendations for A and B, not a direct measure of performance or energy use.
PSU load and compatibility
Interpreting the selected PSU check.
What does selected PSU load mean?
It is estimated component demand divided by the selected PSU's rated output, expressed as a percentage.
Does a larger PSU always consume more electricity?
No. The PC draws power according to its workload. Wall consumption also depends on PSU efficiency and system demand.
Does the calculator check PSU cables and connectors?
No. Confirm CPU, GPU, storage, and other connector requirements separately.
Does the calculator check PSU quality?
No. Rated wattage alone does not assess quality, protections, rail design, condition, or compatibility.
Can wattage alone prove a PSU is suitable?
No. Treat the result as an estimate and check the specific system and PSU specifications.
How is PC PSU wattage calculated?
CPU, GPU, and other component power are added, a chosen headroom percentage is applied, and the result is rounded up to a 50 W PSU size.
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