How to know which power supply to buy?

When it comes to building or upgrading a computer, one of the essential components to consider is the power supply unit (PSU). Selecting the right power supply may seem daunting at first, but with a little understanding and careful evaluation, you can make an informed decision. In this article, we will guide you through the process of how to know which power supply to buy.

Understanding Power Supply Basics

Before diving into the selection process, it’s essential to have a basic understanding of power supply units. A power supply unit converts the alternating current (AC) from your wall socket into direct current (DC) that your computer’s components can use. It provides the necessary power for all your hardware components to operate smoothly.

The Wattage Requirements

Determining the power supply’s wattage is crucial as it directly affects the performance and stability of your system. To find out how much wattage your PC requires, you need to consider the power needs of all the components inside your computer. These include the processor, graphics card, storage drives, and other peripherals.

The easiest way to determine your system’s power requirements is by using an online power supply calculator that considers all the specifications of your components. Simply input the details, and it will calculate the approximate wattage needed.

**How to know which power supply to buy?** After calculating the wattage, you need to choose a power supply that meets or exceeds the total wattage requirements of your computer.

Efficiency and Certification

Power supplies come with various efficiency ratings, which indicate how well they convert AC power to DC power. Higher efficiency ratings result in less wasted energy and reduced operating costs. Look for power supplies that are 80 Plus certified or even higher, such as 80 Plus Bronze, Silver, Gold, or Platinum, to ensure energy efficiency.

Modularity and Cables

Modularity refers to the ability to connect or disconnect cables from the power supply. Modular power supplies provide flexibility, allowing you to install only the necessary cables, reducing clutter inside your computer case. Non-modular power supplies come with fixed cables, which might impact airflow and make cable management more challenging.

Size and Form Factor

Power supplies come in various sizes and form factors, with ATX being the most common. Ensure the power supply you choose matches the form factor of your computer case. Standard ATX power supplies should fit most cases, but it’s always prudent to double-check compatibility.

Quality and Brand Reputation

Choosing a reputable brand and reliable model is vital to ensure the longevity and stability of your power supply. Opt for well-known manufacturers with positive user reviews to minimize the risk of failure or instability.

Noise Levels

The noise produced by a power supply can be bothersome, especially if you prefer a quieter computer. Look for power supplies that feature quiet fan technologies and are designed for minimal noise output.


Power supplies come at various price points, depending on their quality, efficiency, and additional features. Set a budget and look for a power supply that strikes the right balance between your requirements and your financial limitations.

Aesthetics and RGB Lighting

If you are into customizing the appearance of your computer, you might prefer a power supply with RGB lighting or a specific color scheme to match your setup. However, remember to prioritize functionality and performance over aesthetics.

Frequently Asked Questions

1. Can I use a power supply with a higher wattage than required?

Yes, using a power supply with a higher wattage is perfectly acceptable and can even be beneficial as it provides more headroom for future upgrades.

2. Can I use a power supply with a lower wattage than required?

Using a lower wattage power supply might cause stability issues, system crashes, or even damage to your components. It is recommended to always choose a power supply that meets or exceeds your system’s power requirements.

3. Can I use a server power supply in a regular desktop computer?

While it is technically possible, server power supplies are not designed for regular desktop computers and may require modifications or adapters. It is best to choose a power supply specifically designed for desktop use.

4. Is it better to have a single 12v rail or multiple rails?

Having either a single 12v rail or multiple rails does not significantly impact performance or stability. It mainly comes down to personal preference.

5. What is the difference between an ATX and an EPS power supply?

ATX power supplies are designed for regular desktop computers, while EPS (Extended Power Supply) power supplies are geared towards servers and workstations. Make sure to choose the right form factor for your system.

6. Can a power supply affect gaming performance?

While a power supply does not directly impact gaming performance, choosing an inadequate power supply can lead to system instability and crashes, negatively affecting your gaming experience.

7. Are power supply calculators accurate?

Power supply calculators provide a rough estimate of your system’s power requirements but may not consider all individual component variations. It’s always recommended to choose a power supply with a slightly higher wattage than the calculated result.

8. Can I mix different power supply cables?

It is strongly advised not to mix different power supply cables, even if they fit. Each power supply model has its unique pinout configuration, and using incompatible cables can result in damage to your components.

9. Is a power supply with active power factor correction (PFC) necessary?

Power supplies with active power factor correction (PFC) are more efficient and can help reduce your electricity bills. While it is not necessary, it is beneficial to choose a power supply with active PFC.

10. Do I need a power supply with a higher efficiency rating if I am not running my computer 24/7?

While running your computer continuously may yield energy savings with a higher efficiency rating, choosing a more efficient power supply can still be beneficial by reducing heat output, prolonging its lifespan, and providing a more stable power delivery.

11. Can a power supply be reused in a new build?

In most cases, a power supply can be reused in a new build as long as it meets the power requirements and is compatible with the new components and form factor.

12. Can a power supply improve overall system performance?

While a power supply itself does not directly improve system performance, choosing a reliable and efficient power supply ensures stable power delivery to your components, ultimately contributing to a smooth and reliable overall system performance.

**How to know which power supply to buy?** By considering factors such as wattage requirements, efficiency, modularity, compatibility, and brand reputation, you can confidently make an informed decision when purchasing a power supply for your computer.

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