The Problems w/Fanless ATX PSUs

PSUs: The source of DC power for all components in the PC & often a big noise source.

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MikeC
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Post by MikeC » Sun Jun 06, 2004 10:26 pm

That Yesico looks like a lot like variant of the Coolmax TaurusPSU. Very similar casing.

AFAIK, virtually all PC PSUs are made in Asia. Before, there was a lot of production in Taiwan, but now most of the factories are in China, althought the engineering and design seems to be still done in Taiwan. American and European brands buy OEM products from Taiwan & China.

If placed outside the case, a fanless PSU can usually run cool enough iof not it hot weather. Cables can reach if the case is not too big and the cablkes not too short. But it's an expensive way to do it...

pandamonium54
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Post by pandamonium54 » Sun Jun 06, 2004 10:58 pm

Some advantages to fanless PSUs:

1) The low power systems you reference be pretty useful. Most home servers could likely get by with fanless PSUs paired with an VIA EPIA motherboard.

2) Users can treat the entire PSU assembly as just another component that needs some form of cooling. If designing a non standard form factor system (eg: PVR), one could streamline cooling, fanless or otherwise, to also hit the PSU. Or, as in the case of one commercially offered fanless PSU, one could more easily use water cooling components to cool the PSU.

3) While power users are generally comfortable tweaking their system fans, there is a certain degree a hesitation that enters the mind before one actually disassembles a PSU. And from personal experience, PSU capacitor discharges sting like none other!

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Post by PositiveSpin » Fri Sep 16, 2005 9:09 pm

SometimesWarrior wrote:
Pirata wrote:Also, when you left holes open like MikeC does, what about electromagnetic emissions? PCs were designed to be run in closed, metal cases. That dampens electromagnetic emissions a lot.
Think about all the dual-fanned and 120mm PSU's on the market today. There's a big hole at the bottom where all that nasty EMI can get out of the PSU and zap the rest of the PC. Apparently, though, the EMI doesn't seem to be much of a factor after all!

If your computer is in a lab with sensitive equipment, then EMI might be something to consider when you've got the dremel in your hand and you're ready to make Swiss cheese of your case. But for PC's at home or at the office, I just haven't heard much fuss made about EMI emissions.
That's because there's a grille on the 120mm fan. EMI can be (and is) blocked by a grille. Sorry, but your argument is invalid.

link1896
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Post by link1896 » Tue Apr 18, 2006 12:18 am

There is a pile of wires in the average atx psu loom to radiate noise, running the psu externally "could" cause trouble.


As for fanless psu's, running a phantom 500 outside my case has never been a problem, though with everything watercooled the case never warms up.


I'm building a HTPC at the moment and am going to try one of the short cicuit pw-200m psu cards with an external supply.

Stree
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Re: The Problems w/Fanless ATX PSUs

Post by Stree » Tue Jul 31, 2012 11:03 am

Things have moved on quite a bit since the last post in this thread, I have just ventured into fanless PSU territory via a Silver Power SP-S460FL, in an Antec Solo case, Phenom11 x4 955 BE, 2x2gb Performance DDR3 1333, passive Radeon 4350,
Samsung 128GB SSD. I have 2 120mm silent case fans and use an Arctic 7Pro rev2 CPU cooler.
I have run it for a week without the side of the case on, so the case fans are irrelevant for the moment, and it is neither negative nor positively pressured as it is. It runs very very cool. The CPU fan just twitches on idle, and whatever speed it does get up to under any load it remains silent. Very happy with it so far. I was fully prepared to invest some time and money into improving the cooling efficiency all round to cater for the fanless PSU but at this rate there is no point.
The Solo is a MK1 so the PSU is top mounted, which seems bad for heat gathering between it and the case top, but does not seem to happen. Temps checked on various software packages and all low, with similar results.
This is not a heavy use PC or overclocked, so that helps, and probably need a different set up if it had heavier loads demanded of it.

Koldun
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Re: The Problems w/Fanless ATX PSUs

Post by Koldun » Mon Aug 06, 2012 12:25 am

yes indeed, things have come a long way. i have a super flower golden silent (same as the reviewed kingwin stryker), a platinum 500w unit which actually does platinum at 600w as well. its also very cool, and should only have to dissipate ~10w at my load level, which is quite tame considering the size of the heatsinks the mosfets are attached to, and the 180mm fan underneath it. even at full load, there's very little heat and i dont think there will be any issue with longevity of capacitors or other components.

however, i dont think there is much point to fanless psus, even for silence enthusiasts. high end power supplies dont require very much air to keep temperatures in check, one example being the thermaltake toughpower 1275w platinum. it uses a ~60cfm yate loon, and, according to JG, only had a 4-5c rise in temps for most load levels. as such, a 400-500w fanless psu could get by with a 20-30cfm fan, such as a 800rpm slipstream or GT, which would be essentially silent unless you lived in an anechoic chamber.

Silencer56
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Re: The Problems w/Fanless ATX PSUs

Post by Silencer56 » Thu Mar 26, 2015 10:58 pm

Can some mod please remove this horrendously outdated sticky?

Nowadays fanless PSUs can easily be run in a regular case with regular components, at least that's what all the recent reviews of newer passive PSUs show.

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Re: The Problems w/Fanless ATX PSUs

Post by CA_Steve » Fri Mar 27, 2015 8:05 am

Um, you could look at the date of the last post before adding your own?

Silencer56
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Re: The Problems w/Fanless ATX PSUs

Post by Silencer56 » Fri Mar 27, 2015 9:57 am

CA_Steve wrote:Um, you could look at the date of the last post before adding your own?
I know this thread is dead. Still, it is part of your PSU stickies:

viewtopic.php?f=6&t=2658
viewtopic.php?f=6&t=13290

I think newcomers might get very confused if they read this ancient thread.

MikeC
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Re: The Problems w/Fanless ATX PSUs

Post by MikeC » Fri Mar 27, 2015 11:32 am

Silencer56 --

Point taken. See the update of the first post.

Nec_V20
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Re: The Problems w/Fanless ATX PSUs

Post by Nec_V20 » Thu May 05, 2016 6:56 pm

MikeC wrote:Silencer56 --

Point taken. See the update of the first post.
Another point which I think should be mentioned here is that one can have the best of both worlds.

A number of high end PSUs allow for you to use it in fanless mode up to a certain thermal limit above which the fan will start to kick in at low RPMs and gradually increasing when the PSU is under load.

So what is the advantage? In a word - price. You pay a premium for a completely fanless PSU and it is not negligible. An example in the UK would be:
Super Flower Leadex Platinum 550W £81 (hybrid or eco mode fan)
Seasonic SS-520FL2 520W Platinum £125 (fanless)
(I chose the prices from a single vendor which sells both of these PSUs)

The two PSUs are very comparable from the build quality - probably about as good as it gets - so I am comparing like with like.

Realistically the Super Flower could run at 250 Watt output continuously without the fan ever engaging. At 250 Watts the PSU is also in its sweet spot with regard to efficiency (50% rated wattage +/- 6%)

Another thing to remember is that in the UK where we use 240V the same PSU is more efficient than in the US where the mains supply is 110V at peak efficiency (50% load) it will be around 2% more efficient which of course also means less waste heat.

A PSU with fan that only spins up when needed gives one a greater choice with regard to cases than a purely fanless PSU.

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