One fan to cool the entire system? Think it would work?

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frostedflakes
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One fan to cool the entire system? Think it would work?

Post by frostedflakes » Sat Apr 16, 2005 12:15 pm

I've been playing around with this idea for a while. Let me know what you guys think.

Image

For the power supply, I was planning to use a Seasonic S12 330w. I want something as efficient as possible, because it will have to be able to handle all the heat from my system, as well as its own heat.

As far as the heatsink goes, the Scythe NCU-2000 looks promising. It uses a heatpipe, and because it was intended for passive cooling, the fins are spread out, which should make things easier on the 120mm power supply fan.

What do you guys think? Keep in mind that my system does not produce a lot of heat. My video is simply a PCI MX4000, because I'm not a gamer. I have a single Seagate Barracuda IV 40gb, a CD burner, and a 35w mobile (soon to be 25w Turion mobile; more on that soon). So I think this can be done, but I want to hear your suggestions on how I may improve the design.

sthayashi
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Post by sthayashi » Sat Apr 16, 2005 1:36 pm

I think it's possible. Read up on what Bluefront did.

frostedflakes
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Post by frostedflakes » Sat Apr 16, 2005 1:49 pm

Guess I'm not the first one to think of this. Thanks for the link, maybe it'll give me some ideas.

Bluefront
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Post by Bluefront » Sun Apr 17, 2005 1:30 am

Basically your drawing is the same as my final design, with a few differences. I have a second intake at the rear (where the rear case fan used to be). And I added an 80 mm fan between the drives, because I never got the drive temp low enough to suit me without that extra fan.

It's been in use for six months as my primary computer....no problems. As you indicate airflow is the main concern with this design. But it works well...very quiet.

If you build a computer like this, you'll have one of only a few computers running on one fan. It would be easy with a low-power CPU.....but more of a challenge with a modern processor. Mine runs on a P4-2.66.

Good luck.

frostedflakes
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Post by frostedflakes » Sun Apr 17, 2005 8:05 am

I definitely plan to give it a shot. I think the hardest part will be building a duct to my liking. Because the heatsink and power supply fan aren't likely to line up right on top of each other, I'll need to make a custom shroud to connect the two. I was tossing around the idea of making a fiberglass shroud myself, then painting it black so it looks nice. I can't stand ghetto mods, and like stuff to look like it came off a production line. Just a little quirk of mine.

What I may do initially is buy the Seasonic and NCU-2005, and try running the system with just the power supply fan. With the open fins of the Scythe heatsink, I could probably get by with this passive solution if the power supply fan is very close to the heatsink. If not, I could mount an undervolted Yate Loon or something on the NCU-2005 until I was able to build a duct.

frostedflakes
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Post by frostedflakes » Mon May 09, 2005 6:51 pm

Bringing this thread back to the top. Finally have some money to fund this adventure. The Seasonic S12-330 is already ordered and should be here in a week or two, and I'll order the NCU-2005 within the next couple days hopefully.

Will be running at 3700+ mobile (one of the new 62w mobiles based off the San Diego core).

I'll be sure to let you guys know how it works out.

egghat
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Post by egghat » Mon May 09, 2005 11:28 pm

If you put a low power CPU in it and a low power graphic card and a lower power harddisk, this definitly is possible.

Your mobile CPU should work at much lower voltages than the default ones (I've seen someone here who has the new Venice-cores running at 1.1 volt at stock speed, which is nearly as good as my 1.05 volt Low Power Mobile Sempron, despite the fact that his CPU is much faster).

I would put a second fan in, but switch it off, unless the temps get critical. Some BIOSes offer rather good support for this (Lanparty UT nf3 250GB e.g.).

You already bought your PSU, but did you consider buying a passive PSU and putting a 120mm intake fan somewhere in your case. Should work as well.

Will watch your progress.

Bye egghat.

frostedflakes
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Post by frostedflakes » Tue May 10, 2005 4:57 am

I may go ahead and leave the exhaust fan in there, and set it to turn on at 60*C or something like you suggested. :)

But I honestly think temps should stay pretty reasonable at stock volts, especially if I undervolt. If possible, I may even do some overclocking. If this chip can do 2.7-2.8GHz at stock volts like some Venice/San Diego, I'd be pretty happy.

I'm just wondering how much it would mix things up if I threw a higher-end video card in there. I don't game much now, mostly because I'm on dialup. But when I go off to college and have access to broadband, I could see myself getting a mid-range card along the lines of a 6600GT. Guess it isn't anything I need to worry about yet.

alleycat
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Post by alleycat » Tue May 10, 2005 7:33 am

While it's great to have as few fans as possible, you might want to consider that for a given volume of airflow, it is quieter to have two fans running slowly than a single fan running at a higher speed. By pushing all your system's heat through the PSU, its fan may speed up resulting in more noise. Hopefully the Seasonic will be able to handle the additional heat gracefully.

frostedflakes
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Post by frostedflakes » Tue May 10, 2005 8:13 am

Hopefully it will. :D

IsaacKuo
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Post by IsaacKuo » Tue May 10, 2005 8:35 am

I have had plenty of success with one fan designs. My computers are relatively low power, so it works.

If you haven't bought your case yet, you might look around for one which has the PSU "on the side" directly opposite the motherboard instead of "above" the motherboard. I have one case like this, and am thinking of using it to duct a flipped-fan PSU to a traditional CPU heatsink. This makes the duct easy--you just need a plastic cup or bowl and cut it down to size for a stout funnel.

Theoretically, it's better to have the PSU and CPU on the tail end of the airflow chain rather than the head. Ideally, the hard drive is first since it needs the coolest air but generates little heat of its own. However, it'll work either way and it's easier to get a duct to "blow" air at what you want than it is to get it to "suck" air where you want.

BrianE
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Post by BrianE » Tue May 10, 2005 12:09 pm

I certainly hope your idea works out well - I'm trying to concoct a one-fan solution too, but nothing's been finalized yet. It will be interesting to see how well this works out. :)

I think your idea definitely looks good in principle, although I don't have any practical experience to back that up. It's probably important that you ensure:

- low impedance by not using a filter and making sure the front is as open as possible
- that all air "leaks" are sealed up, such as on the front drive bays and other seams

...but I'm sure you thought of these issues already.

Everything is low powered as it is so you'll need less air flow, and everything seems to go "in order" (more or less) of heat production - looks good to me. I think that if you were to install any video card that was good for gaming you might end up throwing a monkey wrench into things and possibly make the system too hot (as it is right now).

Maybe for your duct you could construct something out of glued plexiglass or acrylic sheets and then paint it over? Could be really clean looking if done carefully.

Good luck with your project frostedflakes!

ciz28
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Post by ciz28 » Thu May 12, 2005 6:22 am

I am currently running a PC with just one fan, although it is just a low power media PC. The single 80mm fan in the PSU exhausts air out the back. All of the holes in the case are sealed off except for the vent on the side of the case over the CPU. A duct connects the CPU heasink to the vent so all of the intake air runs over the heatsink. It is just a Duron 750MHz, but it still puts out ~35W of heat. The case is mATX, so there isn't exactly a lot of room to get proper airflow, but I think a standard ATX case should allow you to cool your components sufficiently.

frostedflakes
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Post by frostedflakes » Fri Jun 10, 2005 8:59 am

A minor update on this endeavor.

My Seasonic S12-330 and Scythe NCU-2005 are both here. I have been testing the waters to try and get an idea how well this will work, and if I should even pursue it further.

What I did was tape off every potential intake into the case, save the front intake next to the hard drive cage. This is to direct airflow as much as possible (HDD -> chipset -> CPU -> power supply). I also installed a 120mm fan (undervolted as much as possible without the fan shutting off) on the bottom of the Scythe NCU-2005 blowing upward toward the power supply 120mm intake. Not exactly a duct, but I'm hoping it should fairly accurately simulate the effect of a duct where the PSU fan pulls air through the heatsink.

The CPU and PSU seems to handle the load well. Let it burn for about eight hours, and IIRC the CPU stayed at ~40*C. The air exiting the PSU was very cool, and the fan hadn't ramped up, at least not enough for me to notice.

However, my chipset, memory, and hard drive were burning hot. I have a 4200RPM laptop hard drive coming (consumes ~1/4 the power of my Barracuda IV according to SPCR tests, so I'd assume it should produce ~1/4 of the heat). I also traded my hot TCCD for a gig of what I hope is cooler running BH-5. So hopefully this should solve my problems with the memory and HDD. That still leaves the chipset, though. I think a VIA/SiS/ATi motherboard will be coming in the next month or two. nForce3/4 just runs very hot.

All in all, I think the project has the potential to be a success. I'd like to rig up a fiberglass duct or something that looks pretty nice, but I'll probably wait until I get my new motherboard. Will post more results after I get the new HDD and mem.
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EDIT: Let the paste burn in for a few days, and have tried the same configuration, only with no fan on the CPU heatsink. Temps seem to have stabilized at 53*C while folding. Not too bad at all if you ask me. Motherboard reports PWM temps at 55*C, though (ITE shows this as a red value, 50*C is apparently the upper threshold for this component). Anyone know if this is something I should worry about? I think I have some small heatsinks lying around, I may throw a few on the PWM IC.

Memory, HDD, and chipset are still burning hot. I've also noticed that the top of my case above the CPU gets pretty warm, about 7*C above ambient in the warmest spot according to the probe on my digital multimeter. I don't think the S12's fan is able to move enough air (it's only ramped up to ~800RPM, in free air I believe it was ~600RPM).

What I may do is swap this CPU out with a Turion64 and see what happens. Also plan to begin work on a duct soon.

And just something you may find interesting, power consumption of the entire system under load (F@H) is 82.11w. I'd hope with an undervolted Turion64, the laptop HDD, and lower-power memory, I could get this close to 50w.

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