ATX vs SFX — which power supply should you go for? 

Unsure between ATX and SFX power supplies? Dive into our guide! We compare sizes, compatibility, and performance to help you choose the perfect fit for your PC build!
Muhammad Allayhan
Muhammad Allayhan

Baffled about whether to buy an ATX or an SFX? Well, I can’t blame you because you can’t tell much difference at first glance apart from the size, right? But I’m sure that after going through this article, you’d be able to decide which one’s right for you. So stick with me as we dive into the detailed comparison of these two power supplies. 

Before we go into any details, I need you to know a bit about both the power units. 

You might find it useful to familiarize yourself with our articles on the best power supply for a gaming PC and PSU Tier List for a broader understanding.

A little about ATX PSUs 

atx power supply

Are you looking for a power unit that can provide high power for your robust PC? ATX PSU is the way to go! They have a standard size (150 x 86 x 140 mm) offering up to 2000 watts of power which is quite rare. Most likely you’ll come across ATX units with 300 to 1000 watts range in the market. So if you’re looking for absolute power then you’ll have to compromise a bit on space.

For example, this type of PSU would be ideal for supporting high-end graphics cards like the RTX 3070, 3080, or 3090. You can find some suitable ATX PSUs for these GPUs here.

Because these PSUs take up more space than an SFX PSU. It has a 24-pin main connector that attaches it to your motherboard and also has some peripherals to connect your GPU, storage devices, fans, and other components. 

A little about SFX PSUs 

sfx power supply

Are you a little short on space? Want a PSU that can offer a decent amount of power while not taking up much space? Well, an SFX PSU would be your best bet! These fairly smaller power units (123 x 63.5 x 100 mm) can provide up to 800 watts (sometimes even more) of power. I mean what more can you expect from a smaller unit? So if you have a small PC setup and want a petite power supply that fits right in then there’s no better option than an SFX.  An SFX PSU would fit perfectly within Mini-ITX cases, which are excellent for smaller PC setups.

Now let’s compare the two power units and find out which one is the right fit for you. 

What’s the difference? 

ATX (Advanced Technology eXtended) power supply goes way back in time — it was first released in 1995 by Intel as a refinement of the older AT design. It came with three connectors: 4-pin Floppy, 20-pin ATX, 4-pin Molex, and a supplemental 6-pin connector. Since the launch it has gone through many improvements but it’s not our concern today. So let’s explore the main differences between ATX and SFX. 


The most noticeable difference between the two power supplies is the size. If we talk about ATX; it is 150mm wide x 86mm high and 140mm deep. Thanks to this mammoth size, this power supply can generate crazy power (up to 2000 W) and has far high cooling capacities. 

Conversely, the SFX only measures 123 x 63.5 x 100 mm. But don’t you underestimate it because of the size! It’s almost similar in performance as the ATX but you do have to pay extra for the compact size. 

Moreover, SFX PSUs not only save you space but also don’t heat up as fast as ATX PSUs. This means you can say goodbye to those big noisy fans that distract you while gaming or performing any focus-demanding work. And because of the petite design, it has lesser air pockets making it way more power efficient — going easy on your pocket and the environment. 

Cable length

Another critical factor to keep in mind while deciding between SFX and ATX is the length of their cables. It might seem trivial but this can help you save a lot of extra space. As SFX PSUs are made to save space, they normally have shorter cables. 

On the other hand, ATX ones have longer cables that come in handy for larger PC setups where the components are spread wide out. In this case, you can’t go with an SFX! So it’s always wise to check how much length you need for your system before investing in a PSU. But still, if you don’t get the right size, you can buy an extension cable for some extra room.


When buying a power supply, you must ensure it’s compatible with your system, motherboard, and other components. It should be small enough to fit your system and its connectors should match your motherboard. Plus, don’t forget to check that the PSU has connectors for your GPU and CPU and also has enough connectors for your other peripheral devices. You can’t overlook compatibility if you want to get what you need. 

No doubt, ATX steals the show when it comes to power wattage. But before you go ahead and buy it, check your system’s wattage needs to get the right one. You wouldn’t want to end up with a bulky PSU when you could’ve managed with a small one, right?   

Pros and Cons of ATX

After spending hours on screen, I’ve made a list of some benefits and drawbacks of both kinds of power supplies. Here they are! 


  • It offers more power than an SFX 
  • Perfect for you if you have a big PC setup 
  • More versatility in models
  • Greater range of price options 


  • Incompatible with smaller boxes (Mini-ITX)
  • Greater versatility floods the market with cheaper quality 
  • Low-quality models would have terrible noise levels 
  • It uses larger fans for cooling which are not so soothing for the ears

Pros and Cons of SFX

Let me give you a little heads-up here. After going through the pros, you might think I’m biased. But believe me, I’m just stating the facts here, the decision is yours to make. 

Now let’s take a look at the pros and cons of the little ones (SFX). 


  • Compact size saves you a lot of space
  • It works with ATX computer cases by using an adapter 
  • Installing an SFX is a piece of cake
  • It has shorter cables so no more wire tangles
  • More power efficient and less noisy fan


  • Less variety in models 
  • The high price is due to less demand 
  • Not as durable as ATX 

Parting words 

So, that was all! I hope you got what you needed to decide between an SFX and an ATX. If you have a small setup and don’t need vigorous power for your system, then sticking with an SFX would be the right choice. But if you need a more powerful power supply and have enough space to house it, you’re better off with an ATX. Still can’t make the decision? Confused about something? Don’t hesitate to reach me in the comments below.

Muhammad Allayhan

Muhammad Allayhan, a gaming and PC hardware virtuoso, breathes life into pixelated worlds. A legendary overclocker, he unlocks hidden power in gaming rigs. Navigating from 8-bit realms to today’s masterpieces, Muhammad’s words immerse readers in an ever-evolving digital odyssey. Join him as he reveals the secrets of gaming’s cutting edge.

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