What Is an ATX Power Supply and How to Choose the Right One?

2026-02-03

If you've been looking into PC power supplies, you may have come across the term ATX quite often. But what exactly does it mean, and how can you choose the right one for your setup? In this blog, we'll break down everything you need to know about ATX power supplies in simple terms.

What Does ATX Mean in Power Supply?

ATX is a standard for power supplies used in desktop computers. The primary function of an ATX power supply is to convert the electricity from your wall outlet into the different voltages needed by your PC's internal components. These components include the CPU, graphics card, hard drive, and motherboard.

For example, an ATX power supply typically provides:

12V for powering devices like the CPU, graphics card, and cooling fans.
5V for older components like hard drives or USB ports.
3.3V for certain motherboard functions and chips.

By delivering the right amount of power to each part, the ATX power supply ensures that your computer can operate efficiently and safely. It plays a crucial role in making sure your system runs smoothly without overloading or underpowering any individual component.

ATX vs. SFX Power Supply: What Are the Differences?

When comparing ATX PSU dimensions to SFX PSU dimensions, the main difference lies in their size and compatibility with different cases.

ATX Power Supply: The standard ATX PSU size is 150mm x 140mm x 86mm (width x depth x height). It's ideal for standard-sized desktop cases and offers more power output, making it a better option for high-performance systems or gaming PCs.

SFX Power Supply: The SFX PSU is smaller and designed for compact PC cases. The typical SFX PSU dimensions are 125mm x 100mm x 63.5mm, which makes them ideal for small form factor (SFF) builds or HTPCs (home theater PCs). While they are smaller, SFX power supplies often come with slightly lower power output compared to ATX units.

Both types can be reliable, but when deciding between an ATX vs SFX power supply, you should pick one that suits your case size and your system's power requirements.

What Is an ATX Power Supply and How to Choose the Right One? 1

What Are ATX 3.0 and ATX 3.1 Power Supplies?

ATX 3.0 and ATX 3.1 are the latest standards for ATX power supplies, which include important updates to improve performance and efficiency.

ATX 3.0 Power Supply: Introduced in 2022, the ATX 3.0 standard includes a 12VHPWR connector, which supports new GPUs that require more power, like the NVIDIA RTX 4000 series. It also focuses on improved power efficiency and better cable management.

ATX 3.1 Power Supply: Building on the ATX 3.0 standard, ATX 3.1 improves on the power regulation and voltage stability to enhance the overall performance of the power supply. This is especially important for high-end gaming systems and workstations that require stable and high power output.

If you are building a cutting-edge PC, ATX 3.0 or ATX 3.1 power supplies are the best options to future-proof your system.

If you're simply looking to buy a power supply for everyday use—such as gaming, office work, or studying—then the mainstream, most cost-effective standard ATX power supplies available will fully meet your needs.

ATX Power Supply Connectors: 24 Pin Power Supply

An ATX power supply typically comes with various connectors to power different parts of your computer. The most common and essential connector is the 24-pin power supply connector, which powers the motherboard. This connector is universal and supports most modern motherboards.

Other important connectors include:

8-pin (4+4) CPU connector for the processor

6+2 PCIe connectors for GPUs

SATA power connectors for storage devices (SSDs, HDDs)

When choosing a power supply, make sure it comes with the necessary connectors for your components. For example, if you're planning to run a powerful GPU, you'll need a PSU with 6+2 PCIe connectors to ensure your graphics card gets the required power.

How to Choose the Right ATX Power Supply?

Choosing the right ATX PSU can be overwhelming, but breaking it down into a few key factors can help simplify the process. Here are four important things to consider:

1. Wattage
The wattage of your power supply determines how much power it can deliver to your PC components. The amount of power required primarily depends on the specifications of your GPU and CPU. To accurately calculate the wattage you need, it's recommended to use an online Power Supply Calculator. More importantly, it is advisable to add a 20-30% margin to ensure there is enough headroom for overclocking and future hardware upgrades.

2. Modular, Semi-Modular, and Non-Modular

Modular PSU: Allows you to connect only the cables you need, minimizing cable clutter and improving airflow inside the case.
Semi-Modular PSU: Comes with some cables pre-attached (e.g., the 24-pin connector) while others are removable, giving you some flexibility.
Non-Modular PSU: All cables are permanently attached, which can lead to excess cables and make cable management more challenging.

For optimal cable organization and airflow, modular PSUs are generally the best option. By allowing you to connect only the essential cables, modular PSUs keep your build neat, help reduce heat buildup, and provide a cleaner, more efficient airflow within the case.

3. Lifespan
The lifespan of a power supply is typically measured in MTBF (Mean Time Between Failures), with most PSUs lasting between 5 and 10 years, depending on their quality. Opt for reputable brands that offer warranties and conduct rigorous durability tests to ensure long-lasting performance. It is recommended to choose a PSU with a warranty of 5 years or more, as this indicates that the manufacturer is confident in the product's reliability and longevity.

4. Manufacturer
When selecting an ATX power supply, it's important to stick to trusted manufacturers. Reputable brands guarantee higher efficiency, better warranty terms, and strong customer support. ESGAMING is an emerging brand in the computer peripherals market, with over 300,000 loyal followers on Facebook and YouTube. ESGAMING prioritizes safety and stability, offering high-performance PSUs at competitive prices.
Here's why ESGAMING stands out:

Long Warranty: A 5-year warranty that assures product quality.
Comprehensive Protection: Includes over-voltage, over-current, and short-circuit protection, safeguarding your valuable hardware.
80 PLUS Certification: PSUs with Gold, Bronze, and White certifications help reduce electricity costs.
Fast Shipment: Shipping can be arranged within 7 days.
Support OEM: With over 20 years of professional OEM experience, ESGAMING helps you establish your own brand with high-quality PSUs, with shipments arranged within 30 days.

For a reliable, efficient, and durable PSU, ESGAMING is an excellent choice.

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Conclusion

In summary, the ATX power supply is a critical component of any PC build. Understanding its dimensions, connectors, and the differences between ATX and other power supply form factors will help you choose the right one for your needs. By taking these factors into account, you'll be well-equipped to select the ideal ATX PSU that matches your system requirements, ensuring a stable and reliable power supply for years to come.

About ESGAMING

Founded in 2017, ESGAMING has quickly become a recognized emerging brand in high-performance computer components and accessories. From PC cases and power supplies to now cooling systems, ESGAMING is dedicated to delivering creative, reliable, and well-crafted E-sport solutions for gamers, creators, and PC builders around the world.