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A technician is replacing a power supply. Which two factors should the technician consider when obtaining the replacement part? (Choose two.)

A technician is replacing a power supply. Which two factors should the technician consider when obtaining the replacement part? (Choose two.)

  • type of case
  • input voltage level of 12 or 5 VDC
  • number of internal fans
  • output voltage
  • wattage

When replacing a power supply, the two key factors to consider are the type of case and the wattage of the power supply. These two considerations ensure that the new power supply is physically compatible with the system and meets the system’s power requirements. Let’s explore these factors in more detail and explain why they are essential when selecting the replacement part.

1. Type of Case

The physical form factor of the power supply must match the case type of the computer. Power supplies come in various sizes and shapes, typically defined by their form factor. The most common form factor is ATX (Advanced Technology eXtended), but others such as MicroATX or Mini-ITX are also used, especially in smaller or custom-built systems.

Why It Matters:

  • Fit and Mounting: The power supply must fit properly inside the case. Each case has mounting points designed to hold the power supply in place. If the power supply doesn’t match the case’s form factor, it won’t align with the mounting points or might be too large or too small to fit.
  • Airflow and Ventilation: The type of case affects the airflow patterns inside the system. A properly sized power supply ensures adequate space for airflow, preventing overheating. Some cases are designed with specific airflow patterns in mind, so using the wrong form factor could disrupt these patterns.
  • Cable Management: The type of case often determines how cables are routed inside the system. A mismatched power supply could lead to poor cable management, which not only looks cluttered but can also restrict airflow and make future maintenance more difficult.

To ensure the power supply fits, technicians must verify that the form factor of the replacement unit matches the form factor of the case. For example, if the system uses an ATX case, the technician needs an ATX power supply.

2. Wattage

Wattage is another critical factor when selecting a replacement power supply. It refers to the total amount of electrical power that the PSU can supply to the system components. Every component in a computer system, such as the motherboard, processor, RAM, hard drives, and graphics cards, requires a certain amount of power to function properly.

Why It Matters:

  • System Power Requirements: Every computer system has a specific power demand, determined by the components installed. High-end systems with powerful processors, multiple hard drives, and especially dedicated graphics cards require significantly more power than basic office computers. The technician must calculate the total power requirement of all system components to ensure that the replacement power supply provides sufficient wattage.
  • Future-Proofing: It’s important to consider any potential upgrades to the system. If the user plans to add more components, such as additional storage or a more powerful graphics card, the power supply needs to provide enough wattage to handle these future demands. Installing a power supply that only meets the current requirements can lead to power shortages down the line, causing system instability or hardware failure.
  • Efficiency and Stability: Underpowering a system can result in poor performance, random reboots, or even hardware damage. If the power supply doesn’t provide enough wattage, the components won’t get the energy they need to function properly. Conversely, a power supply with too much wattage doesn’t harm the system, but it might be an unnecessary expense.

How to Calculate Power Needs:

The technician can use online tools or PSU calculators to determine how much wattage the system needs. These calculators ask for details about the system components (CPU, GPU, storage devices, etc.) and recommend a power supply wattage based on the total power consumption. Typically, it’s a good idea to add a margin of about 20-30% above the calculated needs to ensure stability and allow for future expansion.

For example, if a system’s components require a total of 400 watts, the technician should consider a power supply with at least 500-550 watts.

Why the Other Factors Are Less Important:

  • Input Voltage Level of 12 or 5 VDC: While the output voltage levels (such as 12V, 5V, and 3.3V) provided by the power supply are important, they are standard for all modern power supplies. Therefore, technicians typically don’t need to worry about this aspect, as any compatible power supply will offer the necessary voltages. It’s not a factor that varies between different models of power supplies in a significant way, so it’s not a primary consideration when replacing the PSU.
  • Number of Internal Fans: The number of fans in the power supply can impact its cooling efficiency, but this is a secondary concern compared to wattage and case compatibility. Most modern power supplies come with sufficient cooling for typical use cases. Additionally, power supplies are designed to operate within their thermal limits, and they include fans that are sized appropriately for their wattage. Therefore, this is not a top priority for consideration.
  • Output Voltage: While output voltage (typically 12V, 5V, and 3.3V) is crucial for component operation, all modern power supplies are designed to deliver these voltages. This factor is largely standardized across power supplies, making it less of a concern when choosing a replacement.

Conclusion

In summary, when replacing a power supply, the two most critical factors to consider are the type of case and the wattage. The type of case ensures that the new power supply physically fits inside the computer chassis, aligning with mounting points and supporting proper airflow. Meanwhile, the wattage ensures that the power supply can deliver enough power to support the system’s components and any potential future upgrades. Failing to consider these factors can lead to system instability, hardware damage, or even prevent the replacement power supply from fitting into the system at all. By focusing on these two aspects, a technician can ensure a successful power supply replacement that keeps the system running smoothly.