How to make a duct to draw outside air for a HSF?

[jdavis]

It seems to me that making a fairly simple duct to draw cool air from outside the case would be a much better (quieter, cheaper) way of dropping core temps than adding more fans.
I have an Enlight 7237, and an FOP32-1 heatsink. The heatsink fan is 60 mm (duh). I am brainstorming cheap ways of adding a duct that would pull fresh air from the back (probably) of the case (inches away), below the fan that is below the powersupply. Would a second fan mounted to the back of the case (possibly bigger than 60mm), pulling air into the duct, be necessary or effective? How would you go from 60mm square to (however big a decent round duct tube might be)? What would be a cheap easy material for the actual duct? I'm thinking something flexible would be better than say, PVC, for several reasons (turbulence, tolerances, etc). In my mind, the priorities would be 1)effectiveness, 2)ease of construction, and 3)noise. Anyone tried this, or considered it before (come on, I'm sure you have!)?

 

[johncar]

jdavis,
We are strong proponent for ducting room air directly to hs/fan. AT case is easiest as chip socket is only 4+ inches away from inlet fan. Built 2 sided duct from fan frame, mobo and case bottom make up other 2 sides of duct. Used thin aluminum sheet, cut with cheap scissors, but use cardboard at edge near mobo to prevent electrical shorts. Masking tape assembles all pieces of easy cut out the "paper dolls" project, and holds to fan frame, case bottom.

For ATX cases, think direct flow from left side panel would be the best. Cut hole in left panel aiming directly to hs/fan. Cardboard duct to suit panel fan and hs fan. Only problem might be blind assembly. If panel hole is larger than hs/fan, may be able to insert duct after panel is affixed...duct has flanges which fit between panel fan and panel to hold duct in place...you get the general idea. Or invent your own assembly, many ways to do it...but believe side panel location is best.
John C.

 

[Tepin]

Johncar:

I was quite interested in your reply - I've been considering doing just that. So far I've got quite good results with my bottom fan sucking in, a spare 80mm cabletied to the power supply so it hangs about 1 1/2" infront of the CPU fan and a blowhole in the top with an 80mm blowing out. But I've been thinking that if the 80mm I've cabletied were mounted in the side panel blowing outside air at the CPU fan it would be even cooler.

Right now the systems been on about an hour and my MB is at 23.4, CPU at 32.4 and room at about 20 (all deg C) Do you think I'd see a further improvement with the side hole fan?

 

[Confused]

i was also thinking of making a ducting to blow room temp air onto my hsf. with my case closed, the best i was getting at idle with my QuietPC.com Socket A cooler was 32, and full load was about 55/56. When i opened my case, these temps dropped to 22 and 45 respectively (room temp about 20-22. i have a big AT case as well, which i'm gonna mod to take ATX stuff once my dad's moved and i can nick his Dremel. The i was thinking of using a plasic bottle with the ends cut off and attatched to the hsf, and aut through a hole in the side of the case.

With the temp drops with running it with the case open, i then i can prove that drawing room temp air is quieter and does work!

All i need now is a silent or quieter PS fan, and then i won't be able to hear my PC, and have it running cooler!!

BTW, good luck every1 who tries this!

 

[johncar]

Tepin,
Yes, should be a bit cooler, because room air is cooler than case air. Be sure to have a good fit between the duct and the hs/fan.
John C.

 

[jdavis]

Johncar, that is my question: How do you actually connect a duct to the fan? What material could/should the duct be made of? Is a second fan mounted at the mouth of the duct a good idea? How did anyone else solve these problems?

 

[johncar]

jdavis wrote....
>How do you actually connect a duct to the fan?

Fit to hs/fan frame and use some form of tape, masking tape should do.

>What material could/should the duct be made of?

Cardboard or thin plastic sheet, make template, with scissors, close up with masking tape. Trial and error the template with cardboard till it fits OK.

>Is a second fan mounted at the mouth of the duct a good idea?

Yes, one idea would be to design the duct so it has flanges. Then the flanges go between the second fan and the case panel...for a secure fit/grip at that end.
John C.

 

[clumsum]

The easiest way to duct outside air onto the hsf that I know of is to just, .................
Purchase a Fong Kai 320 or even a 603 pc case, ............ the heavy duty plastic duct ......and fan is already installed and waiting to start cooling ...............?

Sorry, ...................... as you know, "there's one in every forum!"