Going to duct. Where to put it?

[Godfodda]

I think I'm finally going to run a duct for my HSF. I've noticed that they're usually run directly out the side panel.

I have a full tower Supercase. This has an area below the PSU that I'm thinking of cutting out to use as a back duct. Any ideas on how this would work? If I do it this way, I plan on placing some sort of air dam near the PSU fan to direct its flow upwards.

Any feedback will be appreciated.


Here is a pic of the rear:

[nihili]

My duct runs from my hsf to the 80mm fan on the back of my mid tower case. I used 3 inch dryer hose at the hs, 4 inch dryer hose at the 80mm, and a 99 cent converter to join them. Works like a charm.

nihili

[Godfodda]

Sorry. Can't figure out how to embed a pic. I'll try it this way. The area in red is where I'm talking about.

[Godfodda]

Originally posted by nihili
My duct runs from my hsf to the 80mm fan on the back of my mid tower case. I used 3 inch dryer hose at the hs, 4 inch dryer hose at the 80mm, and a 99 cent converter to join them. Works like a charm.

nihili

Notice a change in the temps? My main concern with putting it back there was the possibility of sucking warm air back in from the PSU.

[RangerJoe34]

i have an idea, run a duct blowing over the hsf, and then another duct on the opposite side taking the hot air out, then if you want another fan on the top of the hsf, and that should work quite well
just make sure you have enough backpressure on the intake and stuff like that

[nihili]

that's just where mine goes (haven't a clue how to get a picture in here). I've got mine set to blow out so recirculatin psu air isn't an issue. In any case it shouldn't be hard to put something back there to direct the pus air up. It will rise naturally anyway because of the heat.

The duct dropped my full load temps about 6 degrees F. But my fans aren't all that great. I'm pretty sure it would have made a bigger difference with better fans.

What are you going to build the duct out of?

nihili

[nihili]

Originally posted by RangerJoe34
i have an idea, run a duct blowing over the hsf, and then another duct on the opposite side taking the hot air out, then if you want another fan on the top of the hsf, and that should work quite well
just make sure you have enough backpressure on the intake and stuff like that

I've actually toyed with the idea of isolating the heatsink entirely. Run one duct to the top, then make a duct that fits around the rest of the sink and takes the air out of the case. I haven't worked out the details yet, And I'd probably need a case upgrade to pull it off.

nihili

[Godfodda]

Originally posted by nihili

What are you going to build the duct out of?



Haven't decided yet. I was thinking of plastic pipe, but after staring at the inside of the case and the position of the HSF, I'm thinking of something box-like that would eliminate the need for a curve. Something like this:

[eobard]

Don't use anything that isn't smooth. Stuff that will bend by folding in on itself like an acordian would probably impeed air flow with all of the ridges and such. I've thought about using the back of the case as my entrance point but I figured the longer the pipe is from edge of the case to the heatsink the more time the air spends inside the case, possibly picking up heat from the hotter air that's already inside the case. It probably wouldn't make much difference if any but I say why not push things to the limit.

[nihili]

you're right to make the pipe as short as possible, but probably not because of thermal transfer. Rather, the longer the pipe, the more resistance you'll get, and hence less airflow. An important characteristice of a ducting fan is it's static pressure. Deltas are good this way.

dryer duct is not an optimal solution, but it's a cheap and easy way to get started. for about 3 bucks and fifteen minutes of work you can have a duct.

As for avoiding curves in the duct. The best duct is a short straight line to the outside of the case. Just cut a hole in teh side of the case and use the duct to extend the top of the hsf. If you want to duct to the back of the case, then you have to have a bend. In this case it's better to have a curved duct than a right angle duct as shown in the picture. the more extreme the angle, the less flow you'll get.

nihili

[*JEREMY*]

heres what i did for testing out a duct,i cut a hole in the back of the case and mounted a 120mm fan for exhaust then made a triangle duct from cardboard and hot glued it so that it is airtight. The side that presses on the heatsink has a hole cut out slightly smaller than the heatsink so that it does not drop over it and block the cool case air from being sucked thru the heatsink.It dropped my temps 8c over the 7000 rpm ys tech fan i had on it.Lets see if i can get these crappy camcorder pics to work

[*JEREMY*]

...

[Len]

Max PowerZ, I'm a little confused by your pics. In the first pic, is that a fan in the side panel of your case? If so, is it intake or exhaust? In the second pic your duct seems to cover the CPU heastsink. And then 2 followup questions:

1. What is the purpose of the side fan if the duct covers the CPU?

2. If the 120mm is exhausting out the back of the case then isn't that creating a sort of vacuum inside the duct depriving the CPU fan of the air it needs to blow down onto the CPU?

[*JEREMY*]

There is no fan on my heatsink,i have the 120mm intake in the side and a 120 intake in the front,the 120 in the back exhausts .The duct pulls the cold air coming into the case thru the sides of the heatsink fins so instead of blowing air directly on the hs its getting cold air sucked thru it and straight out the case,There is no heat build up in the case from the cpu.Im still amazed at how much my temps are dropping as the room temp is getting colder

[*JEREMY*]

here is a pic to see what i mean better

[Len]

Thanks for the clarification. I get the idea now. Could you please post your case temp? I'm interested in knowing what your case temp is relative to room temp.

One of my reasons for switching to duct cooling is noise reduction. Even though I have a Glaciator which has a quieter fan my PC is still noisier than I would like. I'd like to figure out a way to eliminate most of my case fans. But one problem with eliminating case fans in the internal case temp goes up and then I start to get overheating problems with other things like the GF2 Ultra. I have found these factors are difficult to balance. I can achieve low case & CPU temps with 3 low rpm intake & 3 exhaust case fans but the noise level is higher than I would like. I'm glad I stayed away from that 7000 rpm delta heatsink fan. I'm sure I wouldn't like its noise very much.

[*JEREMY*]

my room temps average about 24c and the case temps are always 1c cooler.I have a sensor placed outside the case and one inside the case out of direct airflow from fan to measure temps.The noise is not bad at all,especially because my case is on the left side of me so i dont really hear the fan on that side and the exhaust fan is in the back. The fan i have in the front is not really loud,mainly just the sound of the air rushing in

[Len]

MaX PowerZ, did you ever test your setup without the duct but with all three fans still running as they are now? In other words, everything the same just remove the duct itself. This would prove the duct is actually providing some benefit. I'm just wondering how much the duct is helping because you already have good airflow through the case with those three 120mm fans although the side fan appears to not quite blow directly on the CPU heatsink.

[*JEREMY*]

yeah before the duct i had a 7000 rpm y.s tech fan,i tried reversing it and everything but could not get my temps to drop,i took off that fan and made a duct for my 120mm fan to blow on it and stuck it out the side of my case before cutting a hole to test and got the same performance,flipped it around and hit the jackpot.I dont know why but having that big of a fan pulling the air thru the heatsink and out the case really works good.I then placed that 120mm fan on side a little low so that it would blow right underneath the duct for cold air supply to pull thru hs.

[Len]

Well, your heatsink exhaust setup is about the only thing I haven't tried yet. Using cardboard and duct tape I created a duct to bring fresh air in from the back of the case and blow it just above my Glaciator and then I had another 80mm fan at the back of the case exhausting air but not connected to the heatsink in any way. With my 3 intake case fans running as usual my case and CPU temps were unchanged and the case was just as noisy since all fans were still running. I tried turning off the Glaciator's fan (it can't be removed) but this resulted in higher CPU temps. After spending too much time on this over the weekend I just gave up for now and put everything back to normal (3 intake fans, 2 exhaust fans, PSU fan exhausting, fan blowing onto video card, Glaciator heatsink/fan).

Basically my goals are:
- Decrease the number of 80mm case fans in use from 7 (incl PSU) to maybe 3. This is mainly to reduce noise.

- At least maintain my current CPU temps which are typically 23C above ambient room temp.

- Keep case temp to 30C or less. It's currently room temp which over summer was 25-26C and is now 22-23C. I am currently able to keep the case at room temp because of all the airflow created by all those fans. I realize that eliminating fans will raise the case temp but if it gets too high then my overclocked Geforce2 Ultra gets unhappy.

- Avoid cutting holes in the case

[heavenly4you2]

Sound to me that you need a good water setup??
I have done the following , I made a duct out of a sheet metal and the smallest side fit's a 80mm fan at the heatsink , i the took a space of about 3cm and made it fit a 90mm fan , then again some space and a hole at the at that fits a 120mm fan. I have put the 120mm fan on the outside of the sidepanel on such place that if i slide in the sidepanel the 120mm fan is lined with the opening at the airduct. this has reduced the temp by 8 degrees celsius and because i used a 24vlt fan for the 120mm wich i can set from 0 to 24vlt i can reduce the noise by letting the 120mm run at 12 vlt. When i need more cooling (hot summer day) than i just give a little more vlt's to the 120mm fan. I hope that this makes sence because my english isn't that good.

[BobbyEwing]

I use a 120mm side fan blowing through a duct made from ventilation tubing for a kitchen fan directly on the HS. This setup has proven to lower my cpu temps significantly, aswell as reducing noise by removing the delta from the HS.