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 Post subject: neat new idea for cooling psu
PostPosted: Sun Jan 19, 2003 4:55 am 
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I've been thinking - one reson my Zalman psu runs so hot (and therefore loud!) is it's trying to cool it'self using warm air inside the case. so...

why not turn the fan around? I have adiquate ventilation due to a whole pile of fans at 5v, so why not let the PSU use the cool air from outside the case - it's loud enough just trying to cool it'self withoout taking on the duties of a case fan!

Of course the immediate problem is that it is contributing heat to the case, but, I think, not significently. See, I've covered up the bottom of the PSU with a bit of tape, so that all the warm air is directed to the two fans mounted on top of my case and staight out!

I still have one small problem to solve - with the PSU sucking in now I'm woried that it's taking in the warm air expelled by my two rar case fans - any sugesions on how I can avoid this?

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 Post subject: Re: neat new idea for cooling psu
PostPosted: Sun Jan 19, 2003 9:02 am 
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PSU internal air temperature and PSU components will be cooler if you turn the fan blow cool air inside PSU. This also corrupts case thermal management, so either you use more case fans, or open the case. And afrer opening the case why not replace PSU fan with a big heatsink.


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PostPosted: Sun Jan 19, 2003 9:04 am 
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Location: Smyrna, Delaware USA
If you tape up the bottom of the psu it is going to get HOT. :shock: The exhaust fan has no air to move through the unit to cool it. :(
If you want to reverse the fans do it then mount the psu upside down so the bottom fan blows out the top of the case.


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 Post subject:
PostPosted: Sun Jan 19, 2003 11:21 am 
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it's ok, there's no fan on the bottom anyway (it's one of tose zalman quiet PSUs (and even if there were it could be safely removed, imho - read up on fan stacking), that vent was there primarily to take hot air rising from the processor, but in my case the air around the cpu is adequately removed by a couple of case fans anyway.

Now I've doen it the re-arangement of the PSU fan works a dream - being thermister controled it now runs much quieter (practically silent) and the hot air is expelled straight back out through the top fans right next to it anyway.

I've kinda re-designed from the whole ATX airflow standards anyway. I figure that the best place to have cool air coming in is where it's neaded most - over hot components. And so I have (ducted) air coming in straight to the CPU, video card and PSU with it leaving via the top, front, back and the opposite side. All my fans are at 5v so they run very quiet and my case runs acceptably cool, with all the normall y hot components very cool.

In fact, I have a notoriously hot Polomino core athlon overclocked in a warm room and still only reading ~ 45c

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 Post subject:
PostPosted: Sun Jan 19, 2003 11:47 am 
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I'd like to see pic of your case. Can you post any?

We're both thinking about the same idea - cooling PSU with fresh cool air (http://forums.silentpcreview.com//viewtopic.php?t=2842), but I'm gonna be a bit of a devil's advocate here.

My only concern is that because your PSU fan is an intake, it will be reusing some of the warm exhaust air from your other case exhausts. The back of a case is always a few degrees warmer than the front. That's why I'm all for ducting in fresh air from the front of the case to cool the PSU.

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 Post subject:
PostPosted: Mon Jan 20, 2003 5:34 am 
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I've just had a great idea - turn the PSU upside down and cut a hole in the top of the case - that way it'll draw air from the top and expell at the back. Could still be a problem with circular flow though. Could reverse the direction of flow?

as for what I'm doing there is a slight problem with it taking in air warm from the back of the case, but it's still much cooler than the air inside. I think what I really need is a small, quater-spherical duct (don't know if this is the real term) like the one here: http://www.dansdata.com/images/badong/backpiece520.jpg to direct the air out and in away from each other.

don't know where I can get one though. Any ideas?

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 Post subject:
PostPosted: Mon Jan 20, 2003 6:01 am 
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I believe I've found the solution...

http://shop.store.yahoo.com/chipcooler/zal80fanduc.html

...wonder if they ship to the uk...?

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 Post subject:
PostPosted: Mon Jan 20, 2003 2:40 pm 
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Alternatively, go to Wickes or something and get a bend piece for drainpipes.
The bottom few inches of a fizzy drink bottle should work too, with a hole cut in the side and perhaps a spare bit of the plastic wedged in to smooth out the corner.


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 Post subject:
PostPosted: Mon Jan 20, 2003 7:08 pm 
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Like the fizzy drinks bottle idea, but I've just made something myself - I've noticed that cutting mats are pretty sound deadening so I've made a duct by cutting up an old one I had lying around (to put on the inside of a blowhole in the hope of attenuating the sound. I had to saw some out some of fan's frame too, the whole thing looks rather nice, and denies sound from my HDD having a direct route out of the case. I'll post pics when I can.

Damn, is that stuff hard to cut, but then again I guess that's the point! :wink:

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 Post subject:
PostPosted: Thu Jan 30, 2003 7:48 am 
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Location: London, UK
i tried using some tumble-dryer ducting to bring cool air in from the back of the case over to the cpu fan, but it ended up raising temps massively! looking back now tho i realise that the fan i had as the intake had a lower cfm than the cpu fan, presumably this was doing bad things with the air flow. i guess you need the fans matched, or is there any benefit to having one with slightly higer cfm than the other? or maybe even not having an intake at all and just bringing the duct from the outside of the case to the cpu fan? presumably this could all be applied to psu's too (desperately tries to stay on topic... :) )


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 Post subject:
PostPosted: Thu Jan 30, 2003 8:07 am 
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well a fan that pushes a small aqmount of air will act as a hinderance to one that pushes a lot more, as they will cause more restistance then they contribute.

In general, stacking fans (ie having them blow into each other) will produce not give you the combined airflow as most people think. It will give you whichever the lowest.

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 Post subject:
PostPosted: Thu Jan 30, 2003 11:19 am 
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i think i remember that stacking fans does increase the pressure of the air, although the actual airflow is the same. higher pressure isn't much use tho, unless u've got very full case! i guess then you only want a fan at one end of the ducting


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 Post subject:
PostPosted: Thu Jan 30, 2003 1:53 pm 
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Location: Fairfax, Virginia, USA
If you have 2 case fans in the rear, one over the other, then I would use poster board to build an enclosure that sections off the entirety of the PSU and the top fan. Take the tape off the PSU, turn the flow around so that the fan is pulling air into the PSU, and use the case fan for exhaust. That should keep the PSU cooler and prevent PSU hear from contributing to the case temp. You can use the Zalman port hood to channel the exhaust air away from the PSU intake at the rear of the case.

This is all assuming that you don't already have a high case temp with 2 fans going in the rear. Limiting one to PSU-detail might create a problem. But its worth a try and cheap.

Haven't tried any of this myself, mind you, but after reading the Intel R&D documents on the SPCR homepage, I'm eager to try using air-flow channels to regulate my case temp.

Good luck!

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