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Difficulty: MediumExpansion Cards and Power Supplies

A system builder is selecting a power supply unit (PSU) for a custom workstation. The planned hardware components have the following continuous power demands:

- Central Processing Unit (CPU): 105 W105\text{ W}
- Dedicated Graphics Card (GPU): 250 W250\text{ W}
- Solid-State Drives and Cooling Fans: 45 W45\text{ W}
- Sound Capture Expansion Card: 20 W20\text{ W}

To prevent power throttling and allow for system longevity, the technician specifies that the total power consumption under full load must not exceed 80%80\% of the power supply's total rated wattage rating (providing a 20%20\% safety capacity margin). Which of the following is the minimum PSU wattage rating required for this system?

  1. A
    420 W420\text{ W}
  2. 525 W525\text{ W}Answer
  3. C
    504 W504\text{ W}
  4. D
    370 W370\text{ W}

Answer

The minimum recommended power supply unit rating is 525 W525\text{ W}.
The total continuous power draw of all components is 105 W+250 W+45 W+20 W=420 W105\text{ W} + 250\text{ W} + 45\text{ W} + 20\text{ W} = 420\text{ W}. To ensure this total load does not exceed 80%80\% of the power supply's continuous capacity rating, divide 420 W420\text{ W} by 0.800.80, which equals 525 W525\text{ W}.

Step-by-Step Solution

1
Calculate total continuous component power draw
105 W+250 W+45 W+20 W=420 W105\text{ W} + 250\text{ W} + 45\text{ W} + 20\text{ W} = 420\text{ W}
Sum all individual hardware power requirements across CPU, GPU, drives/fans, and expansion cards.
2
Apply the 80% maximum target load constraint
420 W0.80=525 W\frac{420\text{ W}}{0.80} = 525\text{ W}
Dividing total power draw by 0.80 establishes the minimum rated PSU wattage needed so that 420 W represents exactly 80% of total capacity.

Key Concept

Power supply unit (PSU) wattage calculation and safety headroom planning
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Topics

Expansion Cards and Power Supplies

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