Are fanless PSUs a good idea?

[heimdali]

Is a fanless PSU a good idea in general?  Do they hold up well enough when room temperatures go up to 38C or more?

 

They don't ventilate themselves and it's not like they could help with ventilating the case and the heat will somehow have to go somewhere.

 

Do they turn themselves off before it gets too hot and can they be monitored like an UPS?  Or will they just melt away?

 

[podkall]

I mean, would anyone buy a PSU that would overheat and die?

 

Well, I guess depends on the PSU quality:

 

[johnt]

Why are you considering a passive PSU? They are quite rare. I have the Corsair SF750 and it's fanless operation below 40% load. At idle and even full CPU load, my fan does not spin. When my GPU whirls up though, then the fan starts. But it's very silent. I can't hear it over my Noctua's.

[aisle9]

Many good, modern PSUs will run fanless below a certain power output anyway. If your system has the fan on one of those running frequently, a fanless PSU shouldn't even be in your thought process. If the fan isn't running often, then you don't need a fanless PSU in the first place.

[heimdali]

4 hours ago, podkall said:

I mean, would anyone buy a PSU that would overheat and die?

People do buy fanless PSUs.  What do fanless PSUs do when they're getting too warm?

 

The case in this video is one of the worst ...

[heimdali]

@johnt and @aisle9

 

I considered a fanless PSU a while ago when I needed one and decided against it.  I didn't like the idea that the PSU could get just hotter and hotter with no way to get rid of the heat like a PSU with a fan could.

 

Now I've seen some threads involving fanless PSU and I'm wondering if fanless PSU are a good idea in general and what happens when they can't get rid of the heat because they don't have a fan.  Either they will have to overheat or turn off before that happens --- in which case it becomes necessary to monitor them just like an UPS --- or they must be designed in such a way that they don't get that hot, and what way is there to prevent that other than to make them more efficient --- in which case they could still get too hot because it could get hot inside the case from other heat sources.

 

So I think they are a very bad idea.  But still people are buying them and apparently they don't seem to fail more than PSUs with fans, or even less.  Or do they?  One advantage they have is that they don't gather as much dust because there's no fan to draw some in.

 

So what is it with fanless PSUs?

 

[johnt]

@heimdali I think it depends on your use case. Perhaps it makes sense to have a passively cooled PC if it’s in a small theater room, maybe someone who just checks emails and Amazon and occasional YouTube. This is basically how the MacBook Pro (14/16 inchers) work. The fan never turns on and it’s amazing. 
 

But I don’t think you’re going to have good results if you plan to game with a passively cooled computer (components in general). 
 

it’s a cool idea. I would totally do it for my HTPC. I like that my sf750 is basically passive below a certain load. It’s the best of both worlds. I game with my main system so the gpu fans are my limiting factor. I can’t hear the psu fan over my aio pump and gpu fans. 

[heimdali]

54 minutes ago, johnt said:

@heimdali I think it depends on your use case.

 

Very limited usage under constant supervision is probably not what fanless PSUs are being sold for and probably not a scenario for which people buy them.  It seems more like they want a PSU that performs in their computer for whatever they're using it for while being quiet and efficient.  The question is if fanless PSUs will actually do that, just like PSUs that have fans.

 

I guess you'd say they won't.  If they don't, are they sold with lots of warnings that identify them as severely limited substitues?

 

[aisle9]

3 hours ago, heimdali said:

So what is it with fanless PSUs?

 

The only use case that comes to mind for me would be a low-powered silent HTPC build (passive CPU cooling) in a case with excellent ventilation. I'm sure there are other use cases for it, maybe in the NAS or Plex server areas that I'm not familiar enough with to guess at.

[johnt]

4 hours ago, heimdali said:

Very limited usage under constant supervision is probably not what fanless PSUs are being sold for and probably not a scenario for which people buy them.

idk about constant supervision. I am sure the units sold by major brands are very safe. I will be honest and say I don't know much about fanless units. From what I am seeing, they generally seem to have low to medium power output, like 400 to 700 watts. I would feel comfortable gaming on those units, but I don't think I would feel comfortable owning one.

 

I still don't fully understand why a completely fanless design exists. For low powered tasks like HTPC or office work, it's not hard to find a unit with a zero rpm mode. For high powered tasks like gaming, your speakers or headphones should drown out the noise.

 

What are you doing in a room at 38C?? I don't go anywhere near my PC when it is hot so that I avoid pumping more hot air into the room.

[Dogzilla07]

9 hours ago, johnt said:

I can’t hear the psu fan over my aio pump and gpu fans.

That's why the first thing I do whenever I get a new part is remove those things.

1. Get a GPU - remove stock fans/de-shroud and put custom 92-120mm full size 25mm and run them below room noise floor

2. remove pump from system, or run pump below room noise floor

3. remove Hard drives

4. remove any fan that came with any other cooler (CPU, M.2 NVMe, Chipset, VRM), and put custom 92-140mm full size 25mm fans instead

 

8 hours ago, heimdali said:

If they don't, are they sold with lots of warnings that identify them as severely limited substitues?

There's no need for any warnings, if the PSU overheats it shuts down, that's how it was designed. They've already been tested for that (the good ones, again getting a good PSU is the most important).

 

And also no need for any supervision, a PSU either works or it doesn't and if it doesn't you either get it RMA-ed or not. At no point should there be any danger to your system, or any loss of your money while the unit is in warranty. Again granted it's a good PSU from a reputable brand.

 

Do keep in mind most fanless PSUs are not silent, on the contrary with the complete lack of fan noise, electrical noise and coil whine comes to the forefront, and can depending on the combination of factors be of extreme annoyance (only full enclosed fanless are immune (like the silverstone 450W nightjar), all others fully open mesh ones are a potential noise disaster.

[heimdali]

4 hours ago, johnt said:

I still don't fully understand why a completely fanless design exists. For low powered tasks like HTPC or office work, it's not hard to find a unit with a zero rpm mode. For high powered tasks like gaming, your speakers or headphones should drown out the noise.

They have been around for a long time, and that includes times when computers were loud.  I resorted to fans with larger diameters, some running at lower voltage than they were rated for.  Only years later others figured it out and started using larger fans ...  PSUs were loud and CPU fans were loud and case fans were loud.  One of the outcomes of computers being loud were fanless PSUs and water cooling; they were invented to make computers less loud.

4 hours ago, johnt said:

What are you doing in a room at 38C?? I don't go anywhere near my PC when it is hot so that I avoid pumping more hot air into the room.

Where else do you go when it's warm?  When it's warm in the summer, it's warm everywhere.  I don't turn my server and my workstation off just because it's warm.  They don't give off so much heat that it would be noticable in the summer.  Electricity is insanely expensive here, so you need power efficient hardware.

[heimdali]

59 minutes ago, Dogzilla07 said:

And also no need for any supervision, a PSU either works or it doesn't and if it doesn't you either get it RMA-ed or not. At no point should there be any danger to your system, or any loss of your money while the unit is in warranty. Again granted it's a good PSU from a reputable brand.

So how don't they overheat?  Are they extremely efficient so that they don't get hot?  It seems much easier to just use a fan that runs when needed ...

59 minutes ago, Dogzilla07 said:

Do keep in mind most fanless PSUs are not silent, on the contrary with the complete lack of fan noise, electrical noise and coil whine comes to the forefront, and can depending on the combination of factors be of extreme annoyance (only full enclosed fanless are immune (like the silverstone 450W nightjar), all others fully open mesh ones are a potential noise disaster.

I never noticed any.  When the PSU still makes noise despite being fanless, then what's the point of being fanless?

[Dogzilla07]

8 hours ago, heimdali said:

So how don't they overheat?  Are they extremely efficient so that they don't get hot?  It seems much easier to just use a fan that runs when needed ...

it's not that they don't overheat, it's that it doesn't matter if they overheat, it doesn't matter for any quality PSU if it overheats, it has a protection OTP, so it just shuts down, no harm no foul.

 

8 hours ago, heimdali said:

I never noticed any.  When the PSU still makes noise despite being fanless, then what's the point of being fanless?

that's a good question xD, the case needs to be quite a bit further away to minimize electrical noise

[heimdali]

33 minutes ago, Dogzilla07 said:

it's not that they don't overheat, it's that it doesn't matter if they overheat, it doesn't matter for any quality PSU if it overheats, it has a protection OTP, so it just shuts down, no harm no foul.

I've seen one going up in smoke but never seen one shut down because it was overheating.  Do the fanless ones overheat sooner?

33 minutes ago, Dogzilla07 said:

that's a good question xD, the case needs to be quite a bit further away to minimize electrical noise

Take the PSU out of its case?

[Dogzilla07]

14 hours ago, heimdali said:

Take the PSU out of its case?

the computer cas needs to be quite further away from ears*

14 hours ago, heimdali said:

I've seen one going up in smoke

a quality PSU should never go up in smoke (as in start a continuous fire and produce constant smoke). And if it does release a bit of smoke (for secondary reasons), it shouldn't take any other part with it. If either of that happens it's badly designed, badly manufactured and/or bad in general

[heimdali]

2 hours ago, Dogzilla07 said:

the computer cas needs to be quite further away from ears*

Ah, ok ...

2 hours ago, Dogzilla07 said:

a quality PSU should never go up in smoke (as in start a continuous fire and produce constant smoke). And if it does release a bit of smoke (for secondary reasons), it shouldn't take any other part with it. If either of that happens it's badly designed, badly manufactured and/or bad in general

It was plugged up with dust, so I can't really blame the PSU.  There's no way around cleaning stuff from time to time with an air compressor unless you operate the hardware in a dust-free environment or perhaps when it's all fanless.

[CatHerder]

AFAIK Seasonic 600W fanless is basically the 1KW fan model but without a fan and limited to 600W.

I bought the fanless 600W Titanium one, and the Internet people™ keep yelling at me that it still needs case fans blowing into it, but i don't really see how.

To me it seems more like as long as there's some space for the heat to passively rise to, it should be fine.

Or am i total clown with these ideas?

 

That being said, Fractal Design Torrent seems pretty sketchy to me.

In that you have your PSU situated upside down. If your PSU had a fan that would be fine, but even i, who doesn't subscribe into the idea of "case fans cooling passive PSUs" find it sketchy that having a PSU with no airflow and no way for the heat to rise into, while being upside down kinda sus.