A/B Testing PC Power Supply (Annual) Calculator FAQ
Answers to common questions about comparing PC power supply efficiency, annual energy use, electricity costs, and savings.
Use these answers to understand the calculator inputs, results, and practical limits of estimating PSU running costs. Results are educational estimates based on the values entered.
General Questions
Basic questions about what the calculator compares.
What does this PC power supply calculator compare?
It compares two PSUs serving the same average PC component load and estimates their annual wall energy use and electricity cost.
Does PSU wattage determine annual power use?
No. Wattage is a capacity rating. Annual use is driven mainly by actual component load, operating time, and efficiency.
What does PSU B represent?
PSU B is the second power supply in the comparison. A positive saving means it is estimated to cost less to run than PSU A.
Inputs and Formula
How to choose and use the main calculator values.
Should I enter PC load or power drawn from the wall?
Enter PC component load before PSU losses. The calculator estimates wall draw using each efficiency percentage.
How do I find a realistic PC component load?
Use a typical measured or estimated load for your normal activities. A single maximum benchmark reading may overstate annual use.
What efficiency should I enter?
Use an efficiency figure relevant to the PSU's expected load where possible. Efficiency can change across the load range.
How are annual kWh calculated?
Wall power in watts is multiplied by hours per day and days per year, then divided by 1000.
Accuracy and Limits
Factors that can cause actual results to differ.
Are the results exact?
No. They are estimates because PC loads and PSU efficiency vary during real use.
Does the calculator include idle, sleep, or standby use?
Not separately. Use an average load that reflects the operating state you want to model, or calculate each state separately.
Does it include monitors and USB devices?
No. It estimates energy drawn through the computer PSU only, not separately powered devices.
Can electricity prices vary during the day?
Yes. If your tariff changes by time, a single rate is a simplified estimate.
Using the Results
How to interpret a comparison outcome.
What does a negative annual saving mean?
It means PSU B is estimated to use more electricity and cost more than PSU A under the entered values.
Does a lower annual running cost mean I should replace my PSU?
The calculator only estimates operating-cost differences. It does not account for purchase price, compatibility, reliability, or replacement considerations.
Can I compare 80 PLUS rated PSUs?
Yes, as a general efficiency comparison, but use efficiency values appropriate to expected load instead of relying only on a label.
Does a higher-wattage PSU always use more electricity?
No. Capacity is not constant consumption; actual load and efficiency determine energy use.
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