This is an experimental setup, so please excuse the un-finished look of it. It's been running successfully for a while, so I thought some of you may like to see it's progress so far.

As you can see in the pictures, I moved the PSU to the bottom of the setup after removing the fan. There is a 120mm fan in the center of the lower case, blowing out through the PSU. This is the only fan in the whole computer, other than the stock Intel cpu fan.

The whole case is sealed at all other openings, so all the air blown out the psu opening has come through the filter at the top, across the board and cpu, down and over the hard drive, through a 4" hole under the hard drive, into the lower case and out through the PSU.

It works perfectly with both fans under-volted. With the cpu fan running about 3200 rpm, and the case fan running about 1500rpm, the setup is very quiet. I'm still working on a new muffler setup for the lower case....more to follow.

I have my HDD enclosed and cooled with a fan (see sign.). I'm thinking that if I get a more suitable material for my enclosure, I can ditch the fan. What do you think of that blue/yellow 'Safety-mat' stuff? Do you think it'll 'trap' a lot of heat? My goal is of course to find something that dampens the noise and 'breaths' at the same time, not trapping any heat.

EDIT: That setup you have there sure looks nice! What processor is that?

The "safety mat" foam is closed cell....does not breathe at all and would
probably cook a hard drive without a fan. Other than that I like the stuff. It's cheap, easy to cut, blocks sounds very well.

It's a Soyo board, 820 chipset, 512 Rambus, Intel PIII-733. Quite a powerful setup.

The shroud you see in the photos, forces the airflow closer to the board and CPU. I've been trying different configurations of this duct, so it's not final yet.

It's logical & creative, like your other work, but those RPM #s don't sound very quiet to me.... in my quiet systems, I rarely have any fan that exceeds 1000-1200 rpm. 3200 from what must be a 40-60mm fan has got to be pretty whiny, no? or does your filter system block/absorb that noise?

Well thanks.....actually the slot1 board was the only one I had left for this experiment. And the cpu heatsink/fan was the only one I had available. It's a small fan, with a built-in shroud around the heatsink. It ran about 4500 rpm, but turned down to 3200 is fairly quiet.

This design does mute the noise from the cpu fan almost completely. There are no openings in the front, top and sides of the case to let out any noise at all. If I put my ear next to the one rear intake port, I can hear the cpu fan.....but that's the only way. The intake filter mutes the sounds, as does the 90 degree bend the airflow makes to enter the intake chamber. When this design progresses, I'll dampen this chamber even further....right now there is no dampening, but it's still quiet.

The exhaust setup is quiet as it is right now.....no acoustic filter installed yet. Having the 120mm fan in the center of the heavy oak case helps, and locating the PSU where it is, blocks the sound quite a bit. I'm working on a new design for this case also. I really need to control the fan speeds better...another A-Open board with Silent-Tek would do the trick.

This design could be applied to almost every tower case and every mother-board/CPU combo......you gain an extremely good air filtration, an airflow which covers the board's hot spots perfectly, the ability to run almost any PSU fanless. Plus many other advantages.

I had a slot 1 P2 at 450Mhz, took off the CPU heatsink fan, and 7V the PSU fan with the PSU inside the case. So I don't think it is necessary to move the PSU outside the case.

I do have another 5V fan blowing at the HD to keep my most valuable asset running.

I think you miss the point of this experimental setup....I was trying to run the computer using one fan in the lower box, with the intake in the former place of the PSU, with a big internally located filter. It works just fine.