When it comes to Power Supply Units (PSUs,) there are mainlytwo form factorsthat dominate the market today—ATX and SFX. The term ‘form factor’ here describes thephysical shape and size of a PSUthat determines how seamlessly it can be integrated into your build.
ATXpower supplies, due to their larger size, are most common forbuilding PCs in full tower and mid-tower cases. It’s an excellent choice for anyone who wants to build a high performance machine. On the flip side,SFXones are relatively smaller in size and a better option for those who prioritizecompact buildswithout compromisingpower supply efficiency.
In this article, I have tried to include every aspect of ATX and SFX power supplies that will help you gain a comprehensive understanding of both of them. By the end, you’ll also be able to decide what will be the best bet for your build.
What is ATX Power Supply
Advanced Technology Extended (ATX) is the mostcommonly used PSU form factorthat is150mm wide,86mm talland140mm deep. While these measurements hold true for the ATX PS/2 variants, the PS/3 variants have a smaller depth of100mm.
You may further notice a slight difference on the dimensions depending upon your PSU manufacturer.
For instance, I took the measurements of myCORSAIR RM850Xand found that its actual dimensions were150mmx86mmx160mminstead.
Below is a list of some pros and cons that will help you better analyze the ATX form factor.
What is SFX Power Supply
SFX power supplies are a real life example for PC builders to prove “Happiness also comes in small packages.” Because two PSUs, one ATX and another SFX (with same specs) can deliver the same power and efficiency to your setup despite the smaller size of the SFX ones.
This kind of PSU is125mm wide,63.5mm talland100mm deep. The SFX PSUs also have aSFX-L variantthat has quite alarger depthfor accommodating larger fans.
Referring to a few SFX PSUs I own, like aCORSAIR SF600, I can confirm that the dimensions specified by the SFX standard are accurate, although it may slightly vary for other models.
Differences Between SFX and ATX Power Supply
SFX and ATX are simply the form factors of a Power Supply Unit. So you may not find a significant difference between them in terms of their working mechanism.
They also share a few similarities like the identicalpower supply connectorsand the efficiency ratings. Meanwhile the higher-end variants of both the kinds come with safety benefits like OCP and OVP.
