Small Form Factor PSU
Small Form Factor PSU

A comprehensive guide to understanding the compatibility of ATX power supplies with Small Form Factor (SFF) Dell or HP computers.

Understanding Small Form Factor (SFF) Computers

Origin and Evolution of SFF Computers

Small Form Factor (SFF) computers, as the name suggests, are compact versions of traditional desktop computers. Their origin traces back to the late ’90s, when space-saving technology began to gain momentum. These machines have come a long way since then, with advancements in technology allowing for more powerful components to fit into increasingly compact cases.

Common Features of SFF Computers

SFF computers are designed to be compact and portable. They often come with integrated components to save space, like onboard graphics and sound cards. Typically, SFF computers also have fewer expansion slots, due to their limited size. However, their compact nature doesn’t mean they compromise on performance. Modern SFF computers can pack quite a punch, rivaling the capabilities of some full-sized desktops.

Pros and Cons of SFF Computers

SFF computers offer several advantages. Their compact size makes them portable and less space-consuming, perfect for small workspaces. They also tend to consume less power, making them energy efficient. However, their compact size can also be a disadvantage. SFF computers have limited expansion capabilities and often require specific or slim components, which may be harder to find or more expensive.

Introduction to Power Supplies

Function of Power Supplies

Power Supply Units (PSUs) are a critical component of any computer. They convert AC power from the mains into low-voltage DC power, which is then used by the computer’s components.

Different Types of Power Supplies

There are several types of power supplies, including ATX, SFX, and TFX. The type of PSU you need depends on your computer case and motherboard. The ATX power supply is the most common type used in full-size desktop computers.

ATX Power Supplies: An Overview

ATX (Advanced Technology eXtended) power supplies are commonly used in full-sized desktop computers. They are larger and provide more power compared to their SFX or TFX counterparts. ATX power supplies typically come with a 24-pin main power connector, which powers the motherboard, and various other connectors for different components.

Power Requirements for SFF Computers

Power Consumption in SFF Computers

While traditional desktop PCs are known for their high power consumption, SFF computers are designed to be more energy efficient. The smaller components typically require less power to operate, which is one of the reasons why SFF computers often come with smaller, less powerful power supplies. However, it’s important to note that the power requirements of an SFF computer can vary significantly depending on the specific components used. High-end processors and graphics cards can still require a substantial amount of power.

Unique Power Supply Designs in SFF Computers

SFF computers often use unique power supply designs to fit into their compact cases. The most common types are TFX (Thin Form Factor) and SFX (Small Form Factor) power supplies. These PSUs are significantly smaller than standard ATX power supplies and are specifically designed to fit into smaller computer cases.

Can You Use an ATX Power Supply with SFF Computers?

The question of whether you can use a standard ATX power supply with an SFF computer is not a straightforward one. There are several factors to consider, including physical constraints and electrical compatibility.

Physical Constraints

Physically, ATX power supplies are larger than the PSUs typically used in SFF computers. This means they may not fit into the smaller cases used for these computers. Before considering an ATX power supply, you should carefully measure your computer case and compare it with the dimensions of the power supply. Remember that you’ll also need space for airflow and cable management.

Electrical Compatibility

Electrical compatibility is another important factor. While most modern power supplies, including ATX, use standardized connectors that should be compatible with any modern motherboard, there’s more to consider. The power supply must provide the right amount of power for your computer’s components. Too little power, and your computer won’t run properly; too much, and you risk damaging your components.

Alternatives to Standard ATX Power Supplies for SFF Computers

When it comes to powering your SFF computer, there are alternatives to the standard ATX power supply that may be more suitable due to their smaller form factor.

TFX Power Supplies

Thin Form Factor (TFX) power supplies are a popular choice for SFF computers. They are compact and designed to fit into smaller cases. TFX power supplies are typically less powerful than ATX power supplies, but they can still provide enough power for most SFF computers.

SFX Power Supplies

Small Form Factor (SFX) power supplies are another option for SFF computers. They are even smaller than TFX power supplies and are commonly used in mini-ITX cases. Like TFX power supplies, SFX power supplies are less powerful than ATX power supplies, but they can still provide sufficient power for most SFF computers.

Conclusion: Can You Use a Standard ATX Power Supply in an SFF Computer?

To sum up, the feasibility of using a standard ATX power supply in an SFF computer primarily depends on the physical dimensions of the computer case and the electrical requirements of the computer’s components. In many instances, ATX power supplies are simply too large to fit into the compact cases used for SFF computers, and alternatives like TFX or SFX power supplies may be more suitable. But, in cases where an SFF computer can accommodate the larger size of an ATX power supply and requires more power, using a standard ATX power supply could be a viable option.

However, it’s important to note that when upgrading or changing any component in your computer, you should ensure compatibility with the rest of your system and follow proper installation procedures to avoid damaging your machine.


1. Are ATX power supplies better than TFX or SFX power supplies?

Not necessarily. While ATX power supplies are generally more powerful, TFX and SFX power supplies are designed to be compact and energy efficient, making them perfect for SFF computers.

2. Can I damage my computer by using the wrong power supply?

Yes. Using a power supply that provides too much or too little power can damage your computer’s components or cause it to malfunction.

3. How can I tell if an ATX power supply will fit in my SFF computer?

First, measure the dimensions of your computer case and the space allocated for the power supply. Then, compare these measurements with the dimensions of the ATX power supply you’re considering.

4. Can I install an ATX power supply myself, or should I get a professional to do it?

If you’re confident in your abilities and understand the risks, you can certainly install the power supply yourself. However, if you’re unsure, it’s always best to consult with a professional to avoid any potential damage to your computer.

5. Why does my SFF computer need a specific type of power supply?

SFF computers are designed to be compact and energy-efficient, which requires a smaller and typically less powerful power supply. Therefore, they often use specific types of power supplies like TFX or SFX that are designed to fit into their compact cases.

Eric Chan

Hi! I’m Eric and I work on the knowledge base at  You can see some of my writings about technology, cellphone repair, and computer repair here.

When I’m not writing about tech I’m playing with my dog or hanging out with my girlfriend.

Shoot me a message at if you want to see a topic discussed or have a correction on something I’ve written.

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