Difference between SFX and ATX PSU

[string111]

Hey there!
I'm pretty new to PC building (doing my second build atm). So I am using the Thermaltake core G3 case, which needs a SFX power supply, because it the case is super slim. So what is actually the difference between an ATX and a SFX PSU? I have been looking but didn't found how they compare to each other on their specs (unfortunately, I only found why they both exist). 

 

Thanks for your help!

 

Greetings Raph!

[minibois]

Their size and thus also screwing holes.

So if your case requires an SFXPSU, you gotta get one of those.The Corsair SF series are quite high quality modular SFX PSUs.

[ricksteendam1]

2 hours ago, string111 said:

Hey there!
I'm pretty new to PC building (doing my second build atm). So I am using the Thermaltake core G3 case, which needs a SFX power supply, because it the case is super slim. So what is actually the difference between an ATX and a SFX PSU? I have been looking but didn't found how they compare to each other on their specs (unfortunately, I only found why they both exist). 

 

Thanks for your help!

 

Greetings Raph!

3

its the difference between form factor an SFX psu in for a smaller case an, SFX case. an atx psu is for the most cases and is so considered the normal size.

the Fabrikant of your case says that they only guarantee this psu will fit: Toughpower SFX 600W Gold

[Guest]

SFX is for small form factor cases, while ATX is for regular ones. That said, you should still always check your case's specifications to see what sort of PSU it requires.

[Stefan Payne]

8 hours ago, string111 said:

So what is actually the difference between an ATX and a SFX PSU?

The SFX ones are way way smaller than the ATX ones and thus can't compete with those well because of the size restrictions their electrical performance has to be worse because for somethings to be good, you need space. Wich you don't have...

And also they have to be louder than ATX PSUs because of that.

 

But there are still some pretty good SFX PSU wich won't kill your computer and are rather decent but can be a bit loud onder medium to higher loads...

So you might want to make the PC as "efficient" (=low power) as possible for whatever you want to do with it.

[Akshatv]

The only difference is of the size. SFX PSUs are less wider and shorter in length compared to ATX PSUs. Also, they come with smaller 80mm or 92mm fan for cooling.

[Stefan Payne]

13 minutes ago, Akshatv said:

The only difference is of the size. SFX PSUs are less wider and shorter in length compared to ATX PSUs. Also, they come with smaller 80mm or 92mm fan for cooling.

No, its not just size.

Its the whole shit that comes with the size restrictions -> worse electrical performance, higher noise and also higher price.

For example a cheapish Bitfenix Formula 450W slaps (almost??) all SFX around with a large trout, is cheaper, less noisy, electrically better than most.

If we go modular, we have more connections as well...

 

So buttom line:
If possible, go with ATX as it offers better choice is cheaper and overall way superior...

The manufacturer didn't seem to use the advantage of the larger area with SFX-L units...

[groot-stuff]

On 9/26/2018 at 4:41 AM, Stefan Payne said:

No, its not just size.

Its the whole shit that comes with the size restrictions -> worse electrical performance, higher noise and also higher price.

For example a cheapish Bitfenix Formula 450W slaps (almost??) all SFX around with a large trout, is cheaper, less noisy, electrically better than most.

If we go modular, we have more connections as well...

 

So buttom line:
If possible, go with ATX as it offers better choice is cheaper and overall way superior...

The manufacturer didn't seem to use the advantage of the larger area with SFX-L units...

In 2023, SFX PSUs may still have higher prices (due to cramming components into a smaller box) and noise levels (due to smaller fans and relatively the same amount of heat in a smaller box)...

 

But the popularity of small form factor builds (ITX & DTX) has brought better quality and higher wattages to SFX PSUs. There are 80+ Gold, Titanium and Platinum ones out there now, which infers their component quality is on-par with similarly rated ATX units.

 

That same popularity, along with rising wattage requirements of modern 2020+ CPUs & GPUs have brought wattage increases to SFX PSUs as well. There are SFX units up to 1000W now, so "electrical performance" isn't necessarily "worse" anymore (as noted above, some have 80+ ratings with 88-92% efficiency). I'm assuming @Stefan's "worse" terminology stems from the fact that years ago, SFX units generally had lower wattages and lower 80+ efficiency ratings.

 

Just wanted to update this thread since it comes up in Google searches in 2023... and things have changed over the last 5 years. If you want an SFX unit for any case, even one that supports ATX PSUs... I (personally) wouldn't hesitate to throw an SFX unit in, especially if there is a good deal or extra space is preferred and potential fan noise isn't a concern.

 

For example: Upgrading my ITX server from a 430W ATX to a 750W SFX unit with an offset bracket is necessary for the extra space it provides (~20mm) for a taller CPU cooler needed for the i7-3770 to R9-5950X upgrade. The PSU in a Lian Li PC-Q25B case sits in front of/over top of the motherboard/CPU cooler, limiting CPU cooler height by the PSU height. Given the server sits in the basement utility room, the clearance gains override both potential fan noise and higher price... SFX makes this round of upgrades possible for me.