Building a PSU intake duct/vent

Post by **Ralf Hutter** » Fri Apr 16, 2004 4:58 am

will0957 wrote:Here's an idea:

there are plenty of cases available that have a top blowhole. Take the fan out, leave the grill. used some thin cardboard or plastic to make a duct from the back of the psu to the "vent" (top blowhole) on the top of your machine.

Nice idea! You can actually put the otherwise useless blowhole to good use.

jAMBAZZ · Post by **jAMBAZZ** » Mon Apr 26, 2004 1:59 am

Ralf Hutter wrote:
will0957 wrote:Here's an idea:

there are plenty of cases available that have a top blowhole. Take the fan out, leave the grill. used some thin cardboard or plastic to make a duct from the back of the psu to the "vent" (top blowhole) on the top of your machine.
Nice idea! You can actually put the otherwise useless blowhole to good use.

- Should the blowhole on top of case pull air out, or push fresh air in?

Trip · Post by **Trip** » Mon Apr 26, 2004 5:33 am

pull fresh air in and exhaust it out the rear of case. ARM does this.

Though you could reverse the regular rear PSU fan to intake and exhaust out the top, you would also need to duct its intake away from the case exhaust. Otherwise you would risk intaking the warm air that just exhausted from your case. See what i mean?

auxilary PSUs like this one or general case exhaust could really use a top blowhole for exhaust if it were ducted away from the reg. PSU's intake (in the inside of the case). Maybe two exhaust blow holes on top (one for reg. PSU and one for case exhaust) would work out alright.

SPCR common sense says that this could be an open source of noise but a duct may reduce the noise somewhat. Rear exhausts usually direct noise out the back where it may be absorbed by a surface but top openings allow noise directly out (w/o the duct).

After cutting out a thick stamped grill, I don't think adding a blowhole would be too difficult, but ducts still scare me. If you mess up, you can always try again, but It'd prob. take me all day and $50 to make a good one (that's a lot of materials)

Gholam · Post by **Gholam** » Mon Apr 26, 2004 10:40 am

Here's an interesting idea I got for a duct: take an old, dead CD-ROM drive, gut all the insides, then use cardboard or plastic to extend the rear all the way to the PSU. Stretch a dense mesh cloth across the front to make it look like a speaker and act like a dust filter, and install sound barriers inside. The rear part can even be made telescoping

This way, you can use standard 5.25" drive mountings, easily remove the whole thing if you need to, etc.

I haven't tried this yet, but I'm planning to move my system to a HEC 6A19 case, which has 120mm fans for intake and exhaust, and this is the solution I set my sights on to reduce PSU noise. The PSU that comes with that case is HEC 300AR-T, which has a temperature sensor and an automatic fan RPM regulator, so the duct should have a positive factor. Will likely cut out both protective meshes in the fan openings and install a grill in the rear one as well.

Post by **Ralf Hutter** » Mon Apr 26, 2004 5:56 pm

Gholam wrote:Here's an interesting idea I got for a duct: take an old, dead CD-ROM drive, gut all the insides, then use cardboard or plastic to extend the rear all the way to the PSU. Stretch a dense mesh cloth across the front to make it look like a speaker and act like a dust filter, and install sound barriers inside. The rear part can even be made telescoping This way, you can use standard 5.25" drive mountings, easily remove the whole thing if you need to, etc.

Now here's a guy who's using his noodle!

Maybe I've finally found a use for all those old 8x to 12x CDrom drives that I can't bear to throw away!

RaNDoMMAI · Post by **RaNDoMMAI** » Mon Apr 26, 2004 8:10 pm

Gholam wrote:Here's an interesting idea I got for a duct: take an old, dead CD-ROM drive, gut all the insides, then use cardboard or plastic to extend the rear all the way to the PSU. Stretch a dense mesh cloth across the front to make it look like a speaker and act like a dust filter, and install sound barriers inside. The rear part can even be made telescoping This way, you can use standard 5.25" drive mountings, easily remove the whole thing if you need to, etc.

simple yet creative.

wonderful

let us all know how it works out

~RaNDoM

Goat_guy · Post by **Goat_guy** » Wed Apr 28, 2004 7:26 pm

Ok, here is my idea for my new watercooling right that I am building soon....

First, I have a 400w coolmax taursus 120mm PSU...im going to move that up about 8 inches (to within about 5" to the back of my DVD burner). Next, rotate it 180deg so the fan vent is facing twords the front of the case. Next, duct the PSU to a 5 1\4 drive using balsa wood. Balsa is awsome. I have 3\4" thick wood, and combined with el-cheapo 1\8" foam, it can stop alot of noise for very cheap. The 10" the sound (barely any anyway) would deaden it even more.

Now, what do I do with a 6"x4" hole in the back of my case, with 5 inches of clearance from the PSU??? RADIATOR! I get a papst or silenx pushing 60CFM through my radiator. Ducted to it draws air from down below, I now have an efficient radiator with NO grill in the way for turbulence! Also, I now have 2 120mm fans blowing out from the top of my case, even further cooling down my case.

So my four 5 1\4 bays would be (top to bottom): PSU exaust, DVD\RW, CD\RW, Resevour for WC'ing. A silent, cool, and efficient computer.

Brian

Matte · Post by **Matte** » Sun Jun 06, 2004 12:27 am

Thought I'd wake this thread up...
I've built a duct for my TP380s out of an air evacuation hose witch pulls air through the top drive bay in my Sonata. The revs of the psu fan are down about 100rpm to about 1400, and I'm pretty pleased with the results. The only problem is that the cpu is about 5c hotter now that case temps are up. Of course the PSU vented this heat before. I guess that the PSU fan revs would lower even more if I got the case and cpu temps down somehow. I imagine that the hot air that leaves the CPU heatsink (Zalman 7000) heats up the duct since the heatsink almost touches the duct. So what do you guys recommend that I do?

Trip · Post by **Trip** » Sun Jun 06, 2004 2:58 am

Which is louder: your case fan or your PSU fan?

Matte · Post by **Matte** » Sun Jun 06, 2004 3:58 am

The psu fan! Thinking about replacing it with a Papst 80mm...

Trip · Post by **Trip** » Sun Jun 06, 2004 5:01 am

Good idea, swapping fans made a noticeable difference for me.

Increasing the case fan speed may drop temps. some.

nova · Post by **nova** » Mon Jun 07, 2004 2:08 am

Matte wrote:Thought I'd wake this thread up...
I've built a duct for my TP380s out of an air evacuation hose witch pulls air through the top drive bay in my Sonata. The revs of the psu fan are down about 100rpm to about 1400, and I'm pretty pleased with the results. The only problem is that the cpu is about 5c hotter now that case temps are up. Of course the PSU vented this heat before. I guess that the PSU fan revs would lower even more if I got the case and cpu temps down somehow. I imagine that the hot air that leaves the CPU heatsink (Zalman 7000) heats up the duct since the heatsink almost touches the duct. So what do you guys recommend that I do?

I used to have a sonata and I can tell you that the TP380 is by far the hottest psu I've used. I don't know what cpu you have but if possible you could try undervolting it. That reduces the heat from the cpu and load on the psu. Use prime95 to test stability of the undervolt.

Matte · Post by **Matte** » Mon Jun 07, 2004 4:54 am

Heh, yea. At stock it's pretty hot, but now that I've built the duct the exhaust temps are down considerably. Under load with the Sonata door open it only raps up about 50rpm, and the exhaust air is barely any hotter then at idle.
The mod I was planning to do is to swap the fan to a Papst and controlling it with a Zalman fanmate. I was planning to run the fan at about 1300rpm. While gaming I'm gonna keep the Sonata door open so the PSU wont get overheated. Do you guys think that this ill work, or am I going to fry th PSU?

nova · Post by **nova** » Mon Jun 07, 2004 7:07 am

That sounds good, what happens when you leave the door on? Since you have a psu duct it should run nicely with a slowed down papst, keep an eye on exhaust temperature though. Taking the door of the case may give you some hot spots when running for an extended period though. I suggest you change the fan and try gaming with the door on while keeping an eye on the temperature of the psu exhaust.

Matte · Post by **Matte** » Mon Jun 07, 2004 9:04 am

When I close the door covering the drive bays, the PSU fan ramps up by about 250-300 rpm.

nova · Post by **nova** » Mon Jun 07, 2004 9:10 am

Oops.. a little missunderstanding there... I thought you meant the side of the case..

Well the door in the sonata is quite restrictive when closed so the ramping up of the fan is expected. Perhaps you should look for another way to get the air in to the psu or remove the door.

Trip · Post by **Trip** » Mon Jun 07, 2004 4:00 pm

If you have a drill, you could drill holes in the bottom of the case near the front.

the_smell · Post by **the_smell** » Sat Jun 12, 2004 11:24 am

Thanks for the suggestion to use your top blow hole as an air intake for a PSU duct - I've just don it with just a sheet of plastic and it has made a real difference

No more PSU noise!

narrasuj · Post by **narrasuj** » Wed Aug 10, 2005 8:04 pm

Hey everybody, I'm new to the whole SPCR thing, so just let me know if I'm asking something redundant. I've been reading all the articles I can and trying to gain information about how to best cool a system and keep it quiet. How about a combination of ideas I've seen on this site? One of them is using a PSU channel (it seems very effective) and the cooling system from the Artic Cooling Silentium T2? I suppose it would require modding of the front bezel and panel to create an opening for a PSU channel, but the CPU and VGA would still benefit from the cool air entering from the back. Any feedback is greatly appreciated, just trying to learn and get a feel for how best to go about doing this!

narrasuj · Post by **narrasuj** » Wed Aug 10, 2005 8:31 pm

Ralf Hutter wrote:
will0957 wrote:Here's an idea:

there are plenty of cases available that have a top blowhole. Take the fan out, leave the grill. used some thin cardboard or plastic to make a duct from the back of the psu to the "vent" (top blowhole) on the top of your machine.
Nice idea! You can actually put the otherwise useless blowhole to good use.

Instead of just takign the fan out completely, why not just reverse it so it's pulling air in, with a PSU channel. It might be overkill and just add noise, but for extreme load, it might be useful. Or if people don't want to open up a PSU to change the fan, run a fanless PSU with an intake blowhole feeding the duct.

Devilsown · Post by **Devilsown** » Sun Oct 23, 2005 7:29 am

Has anyone ever used the intake duct of one of the cdrom's as an outside duct, when placing the PSU fan around?

Hezz · Post by **Hezz** » Fri Mar 24, 2006 10:35 pm

Has anyone tried mounting a 120mm fan PS upside down and cutting a large hole in the top of the case so that the PS just pulls cool air directly from the outside.

This would require only minor case mods. Also, possibly the fan could be reversed so that it pushed air out. It probably would not cool as well this way but using only cool air it might work better.

And then the rear exhaust fan could be left out and another low RPM exhuast fan could be put on the top of the case nearer the front of the case.

So you have the PS isolated using one blow hole and then one more blow hole on the top of the case to evacuate all remaining hot air trapped in the case which would be the most effective place for an exhaust port to be.

A duct from the rear exhaust hole could be made to the CPU fan so it pulls in only fresh outside air. The top blow hole should have about double the CFM of the CPU fan so that it pulls in cool air from other parts of the case.

This might allow for really low fan speeds to remain quiet.

fingers · Post by **fingers** » Thu Mar 30, 2006 8:47 am

(sorry for the slight thread highjack)

If I mount my Seasonic S12-430 upside down that will leave about 20mm clearance with the top of the case, would this be enough to allow me to set up a PSU duct? I am a bit confussed as to whether I can add a duct with a 120mm bottom fan mounted PSU ??

Tibors · Post by **Tibors** » Fri Mar 31, 2006 7:05 am

It might work. But 20mm is so small, that I would not recommend it.

fingers · Post by **fingers** » Fri Mar 31, 2006 7:09 am

Thanks for the advise, I actually had a better look last night and I'm not sure there is even 20mm there. Think I will give it a miss for now. Cheers.

wwenze · Post by **wwenze** » Sat Jun 17, 2006 7:03 pm

Cut away the top of your case, your PSU will be able to get fresh air. At the risk of stuff falling into it.

A Zalman case has it that way.

albatros_la · Post by **albatros_la** » Tue Sep 12, 2006 9:14 am

Nice discussion. That's interesting because the PSU is the only thing remains me to mod on the way to silence. The trouble (or the advantage...) is that it's a one-big-fan model, with a 120mm fan on the bottom side, sucking air off the case. So I ask you if you find dangerous to provide a sound barrier on the outtake of the PSU. Infact a sound barrier stops the noise but also the air flux and in those kind of PSU the air flux is good but really slow with respect a back-fanned PSU. Secondly, the fan rpms are controlled by a thermistor and the barrier maybe will increase the temperature and so the speed of the fan.
What do you think about that? Is the (nice) solution proposed by Lilla suitable also for big fan PSUs or is it good only for the back-fanned ones?

breunor · Post by **breunor** » Wed Sep 13, 2006 4:27 am

I think many people have their cases pushed up near a wall behind the case, and a lot of fan noise is reflected by that surface towards the listener. Rather than make a mostly enclosed duct that blows the air up or down exclusively, perhaps placing a C shaped piece of sound dampening around the opening so that air can vent both up and down (thus just blocking the sides and rear) will limit the sound echoing off the wall without limiting the airflow.

ultrachrome · Post by **ultrachrome** » Wed Sep 13, 2006 8:44 am

albatros_la wrote:Nice discussion. That's interesting because the PSU is the only thing remains me to mod on the way to silence. The trouble (or the advantage...) is that it's a one-big-fan model, with a 120mm fan on the bottom side, sucking air off the case. So I ask you if you find dangerous to provide a sound barrier on the outtake of the PSU. Infact a sound barrier stops the noise but also the air flux and in those kind of PSU the air flux is good but really slow with respect a back-fanned PSU. Secondly, the fan rpms are controlled by a thermistor and the barrier maybe will increase the temperature and so the speed of the fan.
What do you think about that? Is the (nice) solution proposed by Lilla
suitable also for big fan PSUs or is it good only for the back-fanned ones?

With a 120mm fan PSU, I see three possible options:

1) Mount the PSU upside down as recommended above:
- a) Cut a hole in or remove the top of the case above the PSU for air intake
  
  b) In some cases there might be an air gap above the PSU which if large enough (>25mm) may allow you to pull air in from a front drive bay. The air path is slightly circuitous with two 90 degree direction changes but the air flow needed to cool the PSU should be very low and the added restriction may not be a factor.
2) If you have enough space between your CPU heatsink and PSU (mayb e 25mm or more) you could build a slim duct from the drive bay opening that extended under the PSU. Again, airflow should be low enough that restriction may not be a problem.

3) Build a duct that couples your CPU heatsink to the rear case fan. You'll need a tower-style heatsink and 25mm of clearance between the duct and PSU fan. This achieves the same result of the above options by preventing the PSU from ingesting hot air.

I've implemented method #3 mainly because I didn't really know about PSU ducting but had read many posts about CPU ducting. Both methods essentially yield the same result keeping excess heat out of the PSU.

The big advantage of the CPU duct is that it can work with most any motherboard/PSU/case combinations, requires no disassembly to install, and doesn't eat up a drive bay.

albatros_la · Post by **albatros_la** » Wed Sep 13, 2006 9:18 am

I'm just going to buy a big heat-pipe cooler and use it as a passive heat sink for the cpu. I'm really curious about this solution: after replacing the actual fanned cooler maybe the PSU fan will speed up... or not: it depends upon the heat sink efficiency. Maybe a big fanless cooler (TT Sonic Tower) is not a hot spot like a small fanned one and I hope this will help my system to decrase the noise (one less fan) but also the heat in front of PSU air intake. Am I right or is that a pointless solution?

Building a PSU intake duct/vent

Something a little bit different (maybe)....