Ducted Alpha in Aopen AX4GE MAX/Lanboy. Fanless P4 2.66.

Enclosures and acoustic damping to help quiet them.

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Bluefront
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Ducted Alpha in Aopen AX4GE MAX/Lanboy. Fanless P4 2.66.

Post by Bluefront » Sun Jun 15, 2003 3:06 pm

Well I finally got this project started. It's an aluminum duct made from a drier vent part, modified slightly to fit an Alpha heatsink. The fan in the photos has the mount tabs from one side removed. It then fits into the duct and is held tight by the clamp. The fan is mounted to the case normally with four screws...decoupled with a foam gasket.

This is the only mounting for the setup, as on the Alpha end it is a snug fit. I'm still experimenting with different fans....but for now the fan is blowing in at 2000rpm. It's a PCToys stealth fan from CompUSA and fairly quiet. I haven't tried the SilentTec utility, so the fan is blowing at a constant 2000rpms.

This setup really looks good in the aluminum Lanboy....The projection on the Lanboy side panel completely covers the mount, while leaving the aluminum part of the duct visible.

The temps are very good. P4 2.66 idles at 33c and I haven't been able to get it much over 37c. Running the SilentTec utility should be able to lower the fan speed quite a bit and still remain cool. We'll see...

Alpha Duct in Lanboy
Last edited by Bluefront on Fri Jun 20, 2003 5:17 pm, edited 1 time in total.

MikeC
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Post by MikeC » Sun Jun 15, 2003 3:16 pm

Nicely done! Very clean.

How is the noise with vs w/o the duct? I am guessing it is louder with? I know it has to be cooler. I am also guessing that the PSU fan must like it too, less heat drawn in through the PSU so the fan stays runing slow (assuming it is thermistor controlled).

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Post by Bluefront » Sun Jun 15, 2003 5:34 pm

Thanks Mike....I just put this together today and it was never run without the duct setup. I'm sure my idea of quiet and your's differ significantly. This setup eliminates the cpu fan completely. Also, blowing into the case seems quieter to me than blowing out. I'll add a filter to this intake before long, which should further reduce noise.

The SmartBlue PSU that came with the Lanboy is fairly quiet and it is thermistor controlled. So far, so good.

Gekkani
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Post by Gekkani » Mon Jun 16, 2003 4:16 am

Very Nice duct.

But..mmm... I tried with a home made duct w/ my Alpha 8942 and the duct increase the noise :( So I prefer not to use it.

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Post by Bluefront » Fri Jun 20, 2003 5:15 pm

After playing with this setup for a week, I made a few changes, and found out some interesting things. I opened the rear case hole to 92mm and put a 92mm fan in the duct rather than the 80mm one in the original pictures.

I tested the SilentTec utility several different ways. What I discovered was this setup running a P4 2.66 will run under 35c under normal usage, without the duct fan running (stopped by SilentTek). The only output is the PSU fan.....There is an 80mm front case fan running slowly, cooling the two hard drives(blowing in).

The Alpha in the aluminum duct transfers heat into the aluminum of the duct itself....and as you can see in the photos, the PSU has a 92mm fan pulling in air over the duct, cooling it. Also there is airflow through the duct without the duct fan running at all. This is caused by the suction of the PSU fan. The end result is a computer running a hot P4 2.66 being cooled by the PSU fan alone.....most of the time.

You would think the PSU would over-heat...not so. The output temp has never exceeded 37c no matter what I have done. I ran the Sandra CPU burn-in wizard for over an hour. The duct fan turns on at 39c, stays about 1900rpm max, and the CPU never got over 41c. This is 100% CPU usage over an hour.

If you were willing to run the system hotter, you could adjust SilentTec to turn the fan on at a higher temp. Without the duct fan running this is a very quiet setup. I was able to run the computer over three hours doing easy stuff, surfing, etc., without hearing the fan turn on even once..

To make better use of the cooling potential of the PSU fan, I constructed an inner duct (expermental setup for now). This forces the PSU fan to draw more air over the CPU duct, provides more suction through the CPU duct, and causes the duct fan to turn on even later.

It's hotter here today...about 27c ambient. The CPU is running 32C and the duct fan has been off for an hour or more. Hard to believe.

I put up a few more pictures of the inner duct.

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