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Duct querry..or duck qaurel

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Puer Aeternus

Sep 23, 2001
In your head (Ottawa.Canada)
Ha...got your attention!

I attempted a duct sset up in my 1.4 rig and it was pretty "Ghetto" as the term goes. Basicallly I was trying to get air from the fron bay fans to my cpu by the most direct route possible. I am very unfamiliar w/ the duct concept..though it sounds simple enough. My question is this..if I swap my Hard drive fans for a 80mm case fan and rig a tube from it to my cpu..will this provide better cooling? It seems to me that the duct is usually just a tube that connects to outside of the case so the cpu is sucking direct air from outside. I am not sure of whether peeps have a fan helping the flow of air to the cpu...in theory it seems sound..is it?
My results w/ a cardboard tube gave me a 1 degree drop in temp and made a awfull whine sound that told me it was not worth it.
My temps on my 1.4 t bird are 50c at full load....I added some insolation to sides of the case to cut down on sound and that adds to the case temps, but I figure w/ 2 hard drive coolers(5fans in 2 empty bays) blowing in cool air straight across to the cpu and 2 exhaust fans (one on level w/ the cpu and the P/S exhaust above cpu) that my temps should be alot better....is the Volcano 7 a poor performer(steady at 5100 rpm's) or is my fan placement poor?
I'm hoping your idea will work but I have a few changes.

A) I have one 120mm fan instead of 2 80mm fans. This concentrates all power without added turbulence or balancing.

B) I plan to mount the fan on the end of the duct, not on the side of the case. I figure plenty of air will draw through any length of tube witout losing much pressure but making a fan force air through the pipe (by positive pressure) will cause all sorts of lag.
Just to be clear, what I mean is the air will go into the case though the vent, travel down the duct and then hit the fan. This design depends on a very spacious duct, which is totally do-able in my full tower.
Yea, I know about ghetto..........just did a little "ducting" myself last night. Went down to the local h/w store a bought a a short length of 3" diameter aluminum clothes dryer duct. (Did it as more a concept validator kinda thingy) I've got two 80mm fans up front, two 80mm out back and a 60mm Papst on my Swiftech MCX370 h/s.
Now what I did was butt the duct up to the top 80mm fan up front and curve it the best I could to get it as close to the Papst as possible. (Yea, I know it would work heaps better if it was completely sealed on both ends, but it's just not going to happen at this point. Again this was just a theory test.) For being ghetto and all, I still got about a 1c drop and full load temps don't go more than ~7-8c over ambient mobo temp. (30c m/b, 38-40c cpu)
Was it worth it? Probly not at this point. With a little more work maybe.........
Does having a intake fan on one end of the duct offset or unbalance the cp fan on the other end. Is it better to have the cpu drawing air from outside via the duct on it's own..or having a intake fan to send air to the CPU fan. Also, should the intake fan be higher, lower or same rpm as the cpu fan..does it matter?
duct fans

If you can do it with 1 fan do that, but if you do it with 2, use matched fans. The noise is reduced that way somewhat....