Just one fan in the whole case...

readk · Post by **readk** » Fri Jan 30, 2009 5:20 pm

Hi!

I'm planning to build an otherwise passively cooled machine with just a SINGLE 120mm fan for the whole project. Will use a fanless atx power supply and fanless video card and fanless cpu heatsink.

Any advice about:

What case to use?
Desktop (horiz) or Tower (vert)?
Fan at the top, on the side, or at the rear?
Fan blowing in, Fan blowing out?

I am worried about the heat rising off the video card, heating the cpu heatsink then rising more and baking the fanless PS. Maybe a desktop horizontal case would be better or a top fan to blow hot air out or cool air in? What about cases that have the power supply at the bottom?

tehfire · Post by **tehfire** » Fri Jan 30, 2009 6:29 pm

One fan is hard to do, but if you're up for the challenge...

Tower, fan at the rop-rear, blowing out. I'm worried about that fanless PSU...

Post by **NeilBlanchard** » Fri Jan 30, 2009 7:24 pm

Hi,

Which fanless PSU are you going to use? The Silverstone, maybe?

readk · Post by **readk** » Fri Jan 30, 2009 8:09 pm

Yes the Silverstone Nightjar, is this one OK? I thought 300w version would also maybe run cooler.

blackworx · Post by **blackworx** » Fri Jan 30, 2009 8:23 pm

Good luck - it's eminently doable. Fan blowing out, top rear.

dukla2000 · Post by **dukla2000** » Fri Jan 30, 2009 11:58 pm

tehfire wrote:One fan is hard to do, but if you're up for the challenge...

Tower, fan at the rop-rear, blowing out. I'm worried about that fanless PSU...

Seconded - that is more or less my config but have the 120mm in the PSU (not sure the price of fanless PSU is justified). 99% of the time (when CnQ is active) the fan on my CPU hsf is off. And the PSU fan is pretty close to the CPU hsf so removes most of that heat promptly.

My (tower) case has place for a 120mm lower front intake which is not populated but does allow for great case through-flow.

The big gotcha - what are you ambient temps? In the UK (ambients around 20C) it is easy - in warmer climates it is more challenging!

readk · Post by **readk** » Sat Jan 31, 2009 12:15 am

heh. Canada. Not too warm!

I'm thinking that I will do best with the new Lian-Li PC-7f

Solo is probably quieter but then the power supply would be at the top, not sure I want to rely on that with a fanless PS. Maybe I could go external PS.

ntavlas · Post by **ntavlas** » Sat Jan 31, 2009 3:22 am

I think it`s doable, however it`s also possible to make an inaudible computer with an fanned psu, especially if it`s going to be at the bottom.

readk · Post by **readk** » Sat Jan 31, 2009 3:29 am

I literally sleep with my head next to my computer in a tiny apartment so... prefer to go quieter

Tobias · Post by **Tobias** » Sat Jan 31, 2009 5:55 am

The way I did it:

My case is from the P4 era, where cases had to have a sleeved blowhole on the side centered on top of the CPU to be able to cool it properly. Mounting my sleeved fan on the XP-120 with the fins in up-down alignment. Some of the air moves upwards through the PSU and some air blows directly on to the GPU heatsink (mounted on the back of the board) and outwards through the open PCI slits

Only 1 fan deeply embedded in the system. Positive pressure and a filter.

Otherwise, top mounted fan in the rear of the case with a tower heatsink is really the way to go. (either in our out should work)

Of course, you need to mind your GPU, but I get the feeling that you arn't exactly intending to run 4870x2 anyway:)

vertigo · Post by **vertigo** » Sat Jan 31, 2009 6:01 am

Using a fanless PSU as an intake is better (I think) because that way you know it is getting cold air. As an exhaust, you'll not notice if the air it relies on is getting hotter. Your first sign will be when it breaks.

So use the top fan as an exhaust with the bottom PSU as intake. The PSU must allow less air in than the exhaust removes because this will create the negative pressure needed to recycle the air in the case. But of course, it needs sufficient air, so don't leave too many holes open elsewhere, and don't leave the side panel off.

Also don't take a chance, your top fan will be removing hot air and may fail, so connect it to the motherboard and set the BIOS to shutdown if it fails.

readk · Post by **readk** » Sat Jan 31, 2009 10:33 am

Hey guys -

Good info but some conflicting ideas.

Is it best to exhaust through the top of the case or through the rear of the case?

Also should the intake be at the front of the case, or should I block that off and let the power supply be the intake at the bottom?

I can buy any case, so I can find a case with a front mounted power supply even... there are a lot of options here.

jaganath · Post by **jaganath** » Sat Jan 31, 2009 10:42 am

it's not really safe to give advice unless we know what components you are going to put in this case. for a one-fan build, the total power consumption should be less than 100W, and ideally less than 50W.

vertigo · Post by **vertigo** » Sat Jan 31, 2009 11:30 am

Is it best to exhaust through the top of the case or through the rear of the case?

Also should the intake be at the front of the case, or should I block that off and let the power supply be the intake at the bottom?

Readk, if I were you I'd leave this project for later. You really need to have a good understanding of how to use your fan's airflow to cool your PC's components. Knowing where the intake should be is one thing but knowing why it should be there is more important.

Can you answer your own questions? What is the difference between exhausting from the top and exhausting from the rear, and why? Where should be intake be and why?

xan_user · Post by **xan_user** » Sat Jan 31, 2009 11:33 am

jaganath wrote:it's not really safe to give advice unless we know what components you are going to put in this case. for a one-fan build, the total power consumption should be less than 100W, and ideally less than 50W.

and even then temps should be closely monitored while the system is bench marked.

two fans are so much safer when one fan fails, and can be every bit as silent as one.

the additive properties of sound dont mater much till you exceed your ambient noise floor by a measurable amount.

thejamppa · Post by **thejamppa** » Sat Jan 31, 2009 6:05 pm

If I would need to build a system with singel casefan, I would choose case that has large and quiet top fan or modify to fit large 140mm + fan on it as hot air raises. And I would choose system that can be run with Pico PSU.

With regular components its doable. Perhaps your best bet is Antec Mini P180, seal off all other fans and use just the top Antec Big Boy, which isn't half bad fan and produces zero vibrations on low.

colin2 · Post by **colin2** » Sat Jan 31, 2009 10:06 pm

FWIW I have:

Antec Solo
BIOSTAR TA690G
BE-2350 with Ninja
Antec Phantom 500 PSU
four 2.5" HDs and one 3.5"
GIGABYTE GV-NX86T256H video card

All cooled with a single 120mm fan, in the regular place exhausting from the back. AFAIK the backup fan on the Antec PSU has never come on, and the whole thing has been cool and quiet for over a year.

I checked temps carefully at the start with speedfan and direct readings.

The key question is Jaganath's: what components are you going to put inside? The build above was designed for low power consumption, hence low heat and low demands on the PSU. I don't game or play video. But if you move to a more power-hungry CPU and/or video card, you're making more heat inside, more demands on the PSU which means more heat there, and then, yeah, xan_user's advice is right on.

xan_user · Post by **xan_user** » Sat Jan 31, 2009 11:21 pm

The question is basically this..

What do you gain by limiting a build to one fan?

victorhortalives · Post by **victorhortalives** » Sun Feb 01, 2009 4:28 am

Try using an Antec NSK 3480, with a Silverstone in the top half (cools itself through the top grills) and one fan in the bottom half.
SPCR uses this combo in their new quiet room - look for MC's description.

Depending on your "power computing" needs, you might be OK with a Pico instead.

You need to spec your requirements for a better answer (maybe you have done this and I didn't read it)

Xobim · Post by **Xobim** » Sun Feb 01, 2009 5:28 am

I'm just throwing this idea into the group, but why not use a 200mm fan or so on the side-panel and use it as a source for negative pressure? Place a top-down CPU-cooler directly beneath it and block any airhole so that the air flows into the case through the PSU, the videocard and your harddisks. You can even build some sort of duct so all the air flows through the top-down cooler.
The only problem is that there aren't many big fans, so you have to be lucky if you can find a quiet one (The big boy fan from Antec is pretty decent, I've heard).
The Tacens Algeo case has a 250mm fan built-in, but I'm pessimistic about it's noise level...

Furthermore, I must agree with Xan; one fan is a cool idea, but it certainly doesn't hurt if you add a second or third fan to cool your setup. I've got two case fans and a fanned PSU running in my bedroom PC and I've slept next to it without any problem.

vertigo · Post by **vertigo** » Sun Feb 01, 2009 5:43 am

colin2 wrote:FWIW I have:

Antec Solo
BIOSTAR TA690G
BE-2350 with Ninja
Antec Phantom 500 PSU
four 2.5" HDs and one 3.5"
GIGABYTE GV-NX86T256H video card

All cooled with a single 120mm fan, in the regular place exhausting from the back. AFAIK the backup fan on the Antec PSU has never come on, and the whole thing has been cool and quiet for over a year.

Just want to say, doing that allows hot air to enter through the PSU, especially if you have a wall behind the PC. Your PSU is not dissipating much heat so it isn't a problem but with a more powerful system it could get hotter than necessary and could cause problems.

colin2 · Post by **colin2** » Sun Feb 01, 2009 12:23 pm

No quarrel with your assessment, Vertigo. Just to clarify, I pulled out the fan-grilles etc. at the case front, so there's pretty unobstructed airflow from the front to the back and that's what the air does. This case allows very little airflow from the upper PSU chamber into the rest of the case. I have about a foot of clearance behind the case.

The design relies on low power usage. I just touched the back of the PSU and the case above it and felt no warmth at all.

To pick up on Xan's question, my experience is that once you use good fans, noise is mainly a function of total air movement, not the number of fans. It's hard to get quiet if you're moving a lot of air. And of course the air you have to move is a function of the heat you make...

readk · Post by **readk** » Sun Feb 01, 2009 8:36 pm

First, thank you for everyone who offers friendly and helpful opinions and advice.

I am disappointed in some of the comments like "if I were you I'd leave this project for later" that assume I am dumb just because I ask questions. I do have my own answers, but I felt like it was OK to ask questions, and I'd like to hear what more experienced people have to say. If you never ask questions then you never find out anything new. Telling me to give up hope on my project just makes me want to stop reading this forum and stop asking questions. I probably won't ask any more...

As for "why just one fan", it's just to see if it can be done, of course!

I sleep with the computer next to my head

In the past I have tried to build a PC with multiple quiet fans, and it still ended up being loud. Worst case is that if I aim for 1 fan, and I fail, I can just add 1 more fan or turn up the fan speed.

As for what parts I will use... that is partly what I wanted to explore: what parts people have used in the past with success. For many parts, its hard to tell from the specs how they will perform. With a video card, often the power consumption is not part of the specs. Same with a motherboard. With a case, it is hard to tell where to trade off soundproofing with ventilation. I was planning a passive ATI 4650 and an Athlon X2 5050e with passive HR01 sink, since they are (from my research) the lowest power consumers that perform well. Silverstone fanless PS and a SSD for a drive and nothing else. I was thinking of trying to find a Lian Li PC-7f case but now I am looking at cases with top mounted exhaust fans.

N-K · Post by **N-K** » Sun Feb 01, 2009 11:04 pm

I have only one fan running about 500rpm in my Silverstone TJ09 case.
CPU, GPU and PSU are passively cooled.
When you are cooling your hole computer with only one fan, you definitely want to control the airflow as much as possible. All of the intakes have to be at places where they are needed the most.

My PSU is on the bottom of my case and there are holes under it. That way it has SOME intake air to keep keep it cool enough. Some of the heat is also transferred to the aluminum case.

Theres also a place for a fan at the front / center of the case that will provide cool air for the GPU.

I might have fairly hot running components but they all have good coolers and the air is directed to go through critical places. The temps seem fine and I'm satisfied at least.

CPU idling @ 40 Â°C (104 Â°F)
GPU @ 48 Â°C (118 Â°F)

It has been rock solid so far. No problems with it.

You could start with 2 fans and see if it would be quiet enough. If not, just take the other one off. As people have said already, you should definitely keep an eye on the temps at first. Do some stress testing and see if it can handle it.

xan_user · Post by **xan_user** » Mon Feb 02, 2009 8:50 am

N-K wrote:
CPU idling @ 40 Â°C (104 Â°F)
GPU @ 48 Â°C (118 Â°F)

It has been rock solid so far. No problems with it.

You could start with 2 fans and see if it would be quiet enough. If not, just take the other one off. As people have said already, you should definitely keep an eye on the temps at first. Do some stress testing and see if it can handle it.

what are your stressed temps and average ambient room temp? HDD temp ranges?

This might give the OP a temp range to shoot for.

N-K · Post by **N-K** » Mon Feb 02, 2009 9:50 am

The ambient temp is about 22-23 Â°C
CPU gets to ~60Â°C, probably more if GPU is also stressed.
I have made a duct for CPU heatsink from a piece of cardboard.
Can't say any specific numbers about GPU load temperatures but it's somewhere near 70. That's just an estimate.

HDD is completely separated from the rest of the case and it idles at 29Â°C.
When using an SSD, this is not a problem anyway.

xan_user · Post by **xan_user** » Mon Feb 02, 2009 11:35 am

N-K wrote:The ambient temp is about 22-23 Â°C
CPU gets to ~60Â°C, probably more if GPU is also stressed.
I have made a duct for CPU heatsink from a piece of cardboard.
Can't say any specific numbers about GPU load temperatures but it's somewhere near 70. That's just an estimate.

HDD is completely separated from the rest of the case and it idles at 29Â°C.
When using an SSD, this is not a problem anyway.

cool.
the hdd ref was just in case others use this thread for info on single fan setups.
of course SSD is the way to go.

Aris · Post by **Aris** » Mon Feb 02, 2009 2:55 pm

Antec NSK3480 Case
Passive PSU
Single 120mm Fan on rear blowing IN
Tower heatsink on CPU, xigmatek or similar good performer

Its entirely do-able. Its how i have my current gamming rig set up. Got a passive 8800gt with a C2D all with just a single 120mm fan at 6v.

readk · Post by **readk** » Mon Feb 02, 2009 3:09 pm

Aris wrote:Antec NSK3480 Case
Passive PSU
Single 120mm Fan on rear blowing IN
Tower heatsink on CPU, xigmatek or similar good performer

Its entirely do-able. Its how i have my current gamming rig set up. Got a passive 8800gt with a C2D all with just a single 120mm fan at 6v.

Wow that is pretty awesome.

vertigo · Post by **vertigo** » Mon Feb 02, 2009 5:47 pm

readk wrote:First, thank you for everyone who offers friendly and helpful opinions and advice.

I am disappointed in some of the comments like "if I were you I'd leave this project for later" that assume I am dumb just because I ask questions. I do have my own answers, but I felt like it was OK to ask questions, and I'd like to hear what more experienced people have to say. If you never ask questions then you never find out anything new. Telling me to give up hope on my project just makes me want to stop reading this forum and stop asking questions. I probably won't ask any more...

Okay look, it was mentioned that 2 fans can be quiet and your response was that you wanted it to be quieter, but what is quieter than quiet? See, that seemed to suggest that you didn't really understand what had been said. I wasn't trying to be mean or anything, I just thought that you might not be taking seriously that fanless PSUs can easily overheat.

I'm only one person and am just a grouch, so definitely ask questions in future, okay?

There is a thread about how 2 fans are hardly more noisy than one, check it out.

Aris's setup surprises me. Now that I think about it, the hot air from the PSU is not likely to be sucked in again, it'll go above the cooler air like a warm front would. I'm very wary about having the PSU near the fan because my Athlon 500 nearly melted when a replacement PSU had a fan blowing in. I shouldn't be so jumpy, sorry about that.