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Difficulty: EasyExpansion Cards and Power Supplies

A technician is selecting a replacement power supply for a desktop workstation. The calculated peak power consumption of all internal components combined is 250 W250\text{ W}. To ensure system stability and accommodate safety margins, company policy requires adding a 20%20\% power headroom margin above the total peak power draw. Which of the following is the minimum power supply wattage rating the technician should select?

  1. A
    250 W250\text{ W}
  2. 300 W300\text{ W}Answer
  3. C
    270 W270\text{ W}
  4. D
    500 W500\text{ W}

Answer

300 W300\text{ W}
Adding a 20% safety margin to the baseline system power draw of 250 W250\text{ W} requires an additional 50 W50\text{ W} (250 W×0.20250\text{ W} \times 0.20), resulting in a total minimum power supply rating of 300 W300\text{ W}.

Step-by-Step Solution

1
Identify baseline system power consumption
Peak component power draw is 250 W250\text{ W}.
This represents the base wattage demanded by all internal hardware components under load.
2
Calculate the 20% safety margin headroom
Margin = 250 W×0.20=50 W250\text{ W} \times 0.20 = 50\text{ W}.
Adding a percentage overhead ensures the PSU operates efficiently and accounts for power fluctuations.
3
Determine total recommended power supply capacity
250 W+50 W=300 W250\text{ W} + 50\text{ W} = 300\text{ W}.
Combining the base power consumption with the safety margin yields the minimum required wattage rating.

Key Concept

Power supply unit (PSU) wattage calculation with safety margin
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Topics

Expansion Cards and Power Supplies

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