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Convection cooling - yet another passive PC idea

8K views 20 replies 9 participants last post by  nolonger 
#1 ·
So I bought an SSD a while ago, and noticed the improvement in speed straight off. That's not what interests me most about them though. Coupled with my now dead 4890 (replaced by a silent temporary one from 1998), this new innovation gave me an excuse to switch off all my HDDs and fans, stick a pencil in my PSU fan and experiance truly silent computing.
It's a surreal experiance, hearing your own heartbeat as the loudest thing in the room whilst browsing the net.

So it got me thinking. Passive computing. (Hardly a new idea, I know)
My thoughts:
Presumably, in an entirely passive setup, you're going to want to use convection to shift heat. In a standard ATX layout, this is problematic - because GPU heat rises to the CPU cooler.

So - my genius (and apparently unoriginal, much to my distaste) idea is to rotate the motherboard through 90* (clockwise), and have the airflow from bottom to top - effectively in seperate channels for CPU and GPU coolers.

I've hit on a problem though. The orientation of the fins in every GPU cooler I can find is not conducive to this air movement. They all seem to be designed for airflow perpendicular to the card, as opposed to along its length.

If anyone can find me a solution to this problem (and any thoughts on the whole idea) it'd be much appreciated! Nearest I can find is to take a Thermalright Spitfire, and mount it so the heatpipes lie along the card towards the bracket / output end. Naturally, this presents a compatability problem with most cards. [EDIT: Just realised that wouldn't even work, since the left-hand edge of the cooler would intersect with the motherboard]

(Water cooling is a different - in many ways much easier - solution but unfortunately pumps are not silent. Building a convective water cooling solution would be far too complex for me to attempt it).

PS. It strikes me that most externally-venting (ie. stock) coolers would encourage convection if appropriately orientated, but I would prefer a larger surface area.
 
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#5 ·
#6 ·
Well I said I'd prefer a larger surface area - and by god, those two coolers are huge!
The graphics cooler is not in the orientation I'd like, but tbh it's so big it probably wouldn't matter.

As for fans? Well I was considering mounting a pair of 120mm on the bottom for positive pressure. However, I currently have 5 different fan types and only one of them would I consider using. Irritatingly, it's the generic one that I can't identify for love nor money. All the others make regular lil clicking / tapping noises like a slight buzzing - the one I like makes more of a white noise sound that's not noticeable.

On a side note,
I find it strange how Zalman says "noiseless" is <20db at 60cm. I'm trying to create something that'd be silent if you were trying to sleep with your head in the case.

EDIT: Talking of sleep, I must go for now. I will continue this train of thought tomorrow, perhaps.
 
#7 ·
Quote:
Originally Posted by zsolmanz;11835400
Well I said I'd prefer a larger surface area - and by god, those two coolers are huge!
The graphics cooler is not in the orientation I'd like, but tbh it's so big it probably wouldn't matter.

As for fans? Well I was considering mounting a pair of 120mm on the bottom for positive pressure. However, I currently have 5 different fan types and only one of them would I consider using. Irritatingly, it's the generic one that I can't identify for love nor money. All the others make regular lil clicking / tapping noises like a slight buzzing - the one I like makes more of a white noise sound that's not noticeable.

On a side note,
I find it strange how Zalman says "noiseless" is <20db at 60cm. I'm trying to create something that'd silent if you were trying to sleep with your head in the case.
The reason behind saying that below 20db is silent, is because most of the time ambient sound level is about 18 to 19db, so anything at or below that is unheard.
I love the idea of sleeping in your case.
I would recommend a set of Gental Typhoon fans for air movement, they are quiet and move a decent amount of air.
Yes the gpu cooler is so huge it wouldn't even matter.
 
#8 ·
#9 ·
Umm, totally passive ISNT possible with any type of hot components..
http://metku.net/index.html?path=mods/passive/index6
Have a look there, it's a massive case made out of aluminum fins with a massive convection tunnel, and it is still pretty hot..
Have a look at that article, if you know how to use google translate..
And those components are old.. 6800 gt and an opteron..
E: and those suggested coolers won't work, convection wont give enough airflow through fins that dense..
 
#10 ·
Quote:
Originally Posted by thrasherht;11835389
Im not sure they had complete passive cooling in mind when they designed that case, but yes, it would work for that purpose i think.
I think the best way would be to just have really low speed fans for a little bit of air movement.
The way I see it the best orientation for convection is to have your motherboard lying on the table. Provided you have enough surface area in the GPU cooler its orientation won't matter much. I see this in my GT210. It does heat up when used to run more intensive applications, but doesn't overheat simply because the chip can't give more heat than the heatsink can dissipate. It uses a very simplistic design probably made to be run on a regular ATX setup with a fan blowing from the side panel, but works fine even without a fan there.

The idea isn't very hard to execute and I've seen it done in one website actually. I just can't remember where I saw it.
 
#12 ·
Quote:
http://www.zalman.co.kr/ENG/product/...ad.asp?idx=116
there we go, just remembered that case today.
I like how Zalman says this case can silently cool 75W of heat enough to keep the hottest card on the market cool

I think with a little mod this could be relatively easy, have a PCIe extenderand try to orient the graphics card in a way the passive heatsink can efficiently cool it. All you need is to make sure is that the graphics card is secured in place.
 
#13 ·
Quote:
Originally Posted by linkdiablo;11908343
I like how Zalman says this case can silently cool 75W of heat enough to keep the hottest card on the market cool

I think with a little mod this could be relatively easy, have a PCIe extenderand try to orient the graphics card in a way the passive heatsink can efficiently cool it. All you need is to make sure is that the graphics card is secured in place.
You do know how old this computer case is right?
I remember seeing this case like 4 years ago. So 75watts from a graphics card was alot back then.
 
#14 ·
Quote:
Originally Posted by thrasherht;11835437
I would recommend a set of Gental Typhoon fans for air movement, they are quiet and move a decent amount of air.
Good call - I'll take a look.
Quote:
Originally Posted by Skiivari;11873383
Umm, totally passive ISNT possible with any type of hot components..
http://metku.net/index.html?path=mods/passive/index6
Have a look there, it's a massive case made out of aluminum fins with a massive convection tunnel, and it is still pretty hot..
Have a look at that article, if you know how to use google translate..
And those components are old.. 6800 gt and an opteron..
E: and those suggested coolers won't work, convection wont give enough airflow through fins that dense..
I was under the impression that today's CPUs ran cooler than older ones. As for graphics cards? I know for certain that my 4890 couldn't run with the Zalman VF1000 fan off - heated up even when underclocked as much as possible. But that's the point in changing the orientation, and getting a bigger cooler. Forced airflow if necessary - hence speedfan or equivalent.
As for the effect of fin density on convective air flow, I'll have to read into it more - it could be an important factor that I haven't considered.
Quote:
Originally Posted by nolonger;11906825
The way I see it the best orientation for convection is to have your motherboard lying on the table. Provided you have enough surface area in the GPU cooler its orientation won't matter much. I see this in my GT210. It does heat up when used to run more intensive applications, but doesn't overheat simply because the chip can't give more heat than the heatsink can dissipate. It uses a very simplistic design probably made to be run on a regular ATX setup with a fan blowing from the side panel, but works fine even without a fan there.

The idea isn't very hard to execute and I've seen it done in one website actually. I just can't remember where I saw it.
That strikes me as the worst way to do it - the fin profile of the both cpu cooler (unless it's a flower) and gpu cooler will be completely wrong for convectional flow. But each to his own...
Quote:
Originally Posted by thrasherht;11906866
http://www.zalman.co.kr/ENG/product/Product_Read.asp?idx=116
there we go, just remembered that case today.
That's way too difficult and custom for what I had in mind, but I sure would like to steal their PSU. See, I have a vague idea in mind but nowhere to put the PSU.
Quote:
Originally Posted by omega17;11835377
someone *almost* already thought of it

http://www.bit-tech.net/hardware/cases/2010/05/04/first-look-silverstone-raven-rv02-e/1
...
That's pretty much /thread right there. It's big though - I'm sure this could be done in a more compact way - and if the case is smaller (or at least narrower), there's a better chance of a proper convection flow. I suspect that case relies a lot on its fans, although at 180mm I doubt they're very loud.
 
#15 ·
#16 ·
FYI, I don't think the Accelero S1 will work with a 4890. I couldn't get it to work with mine...mounting hole orientation problem.

I think the best way to get a silent computer is to get a plain case, mod with a 360mm Rexflo fan, and sit back and enjoy.
 
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