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Air Duct

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Senior SMP Gawd
Jan 15, 2001
SK6 Heat sink,ys 27 cfm fan.had high temps of 53c on my 1.2 at 1.46

Have fans like crazy on case,so I took 2 cans taped them together,and created a duct that draws air from the outside of case,sealed duct to heat sink fan and now I top out at 46c.

It appears all my attemps at sending outside air into case were not working,also system temp dropped by 1c.Now when my delta 38 cfm arrives I will go to home depot and make a nice duct for my system
Have installed four fans into my system no duct work.
One fan at the rear of mycoses blowing out,one on top of the case sucking in, and twin fans on the side panel.
I am running a slot a t-bird 900 over clocked,temp at startup 82F,rock steady at 89F or 32C. Cool running will get you everything you want.
ducts work really well and they are cheap to build out of cardboard.
I have two fans [ power supply fans] running off an outside second power supply. One fan pulling air in other pulling extra fresh air in and over CPU Heat sink. Droped my temps from 50C to 45C. Thinking of cutting hole in front for more air for front fan.
Remember its not a good idea to use metal for a duct one mistake and you can fry allot of stuff, making them out of cardboard or plastic is the way to go. Also make sure your duct does not touch the fan on your HS or the vibrations will cause excess noise.

Air flow can be very quirky. By putting an Indoor/outdoor thermometer probe at various points, I discovered that in a completely open case there was a halo of heat surrounding the HSF. Apparently the input of the fan pulls the hot air from the sink right back to the HSF. Putting a fan to blow away the cloud can increase the temp. A fan can be very effective at blocking air flow by overpowering the flow from another fan. The best positioning turned out to be pointing the auxiliary fan at the HSF at a 45 degree angle about 8 inches away.

Adding yet another fan never lowered the temp any, and without very exact direction, usually increased the temp, apparently by creating stagnant spots where the air flows interfere.

The shape of the interior of a case is not very conducive to air flow. There can be hot spots of stagnant air even with a large volume of air entering and exiting the case. Baffles and ducts added within the case could possibly improve circulation to particular points, but without testing, you are as likely as not to make things worse.
outhouse (Jul 15, 2001 01:58 a.m.):
Remember its not a good idea to use metal for a duct one mistake and you can fry allot of stuff, making them out of cardboard or plastic is the way to go.

You could wrap the metal with cloth duct tape. It would cut down the vibrations too.

Put Mortite rope caulk (like modeling clay) between the cans and the fan to damp virbrations.