Fanless Nirvana....Bluefront's Zen.

Bluefront · Post by **Bluefront** » Sun Oct 15, 2006 11:10 am

This is my first fanless PSU....the Fortron 300w Zen. After reading the SPCR review some time ago, the wheels were spinning, trying to figure a setup that would work with the thing. The knock against fanless PSUs is that they dump extra heat inside the case, making it more difficult to keep everything cool.

Well this setup avoids that problem completely. The Zen has excellent flow-through ventilation, but mounted normally, it has a relatively small opening to the outside. If you run a negative pressure case, the outside opening of the Zen will become an intake......and you will be sucking heat from the PSU back into the case. In my solution I mounted the Zen partially outside the case. And I am running a totally positive pressure case, so the airflow is through the Zen blowing outward.

I did a few more things to insure adequate airflow through the Zen. I added an air deflector on the top of the Ninja heatsink, so the Zen is getting almost totally ambient air being blown through it. The one rear case fan in now doing double-duty.....supplying both the Zen and the Ninja with ambient air.

I thought this small deflector would detract from the CPU cooling.....didn't happen. The CPU still runs at the same temp, at the same rpm, as before the addition of the Zen.

The other mod consists of a small hole cut into the right side of the inner case, matching the verntilation holes on that side of the Zen, holes normally blocked by the case. This opening allows more airflow through the zen, airflow that goes into a passive air channel between the inner case, and the outer case panel.

This outer air channel is the primary exit point for the case exhaust. The exhaust comes out of a slot about 15mm tall that runs the length of the top of the case. I also have a 120mm hole over the top of the Zen.....the old exhaust point of the previous PSU. This hole will probably be eliminated when I make a new top for this setup.....based on a Gateway Series E case.

This Zen is a winner so far......The maximum temp of the thing has been about 36C doing benchmarking, Ambient about 23C. Love it. FWIW...with a negative pressure case, this particular mod would work as well, the difference being the case fan would suck ambient air through the Zen, and blow it outside the case.

theyangster · Post by **theyangster** » Sun Oct 15, 2006 5:05 pm

impressive

how much does the psu cost?

and you're not worried that heat from the back of the psu might be sucked in or you'd probably added something later

jaganath · Post by **jaganath** » Mon Oct 16, 2006 12:54 am

Nirvana

So you're actually using the rear exhaust fan as an intake, and this feeds airflow to both the Ninja and the Zen? (LOL, the accumulation of Buddhist terms continues

) You say the hot air exits through a slot at the top of the case but all I can see in the pics is a jumble of cables there?

Some more pics would be nice (w/ case closed pretty please

).

Bluefront · Post by **Bluefront** » Mon Oct 16, 2006 2:58 am

This thing is hard to photograph. When the sides and top are removed, the air channels are not there any longer. The long photo shows the main exhaust channel. The interior of this case is under positive pressure, the heated air goes upward, through the big holes in the top framework, around the side of the wooden top panel (there's about 1'2" clearance between the wood and the case), and out through the slot......visible in the last photo.

Like I said,,,,hard to picture and explain. The other air channel (third photo) is between the case framework and the outer panel. this is also about 1/2" thick. The bottom is open.....so there is passive airflow from the bottom, over the back of the MB, and out through the upper slot. This airflow is aided by the positive case pressure, which pulls airflow in from the bottom of this outer channel, as it goes upward on the interior of the case and out the top slot.

The other exhaust for the case is through the ventilation holes in the Zen....aided by the zen being partially mounted outside the case. This gives more holes for exhaust. I have an air filter assy for the rear case fan (no photos yet). It extends back about 4" and prevents the intake fan from drawing in any exhaust.

This whole setup runs on two fans....the one case fan blowing inward in the photos, and a bottom fan blowing inward which cools the HD and video card. I have one lower opening...one PCI slot is open. This promotes a small bit of airflow over the video card and out the rear of the case. I'm not finished with the whole setup yet. Still working on it.

This setup is running a P4-3.4.....fairly hot CPU (about 95w). It idles about 34C as you see it with the air filter assy in place. Ambient of 23C. Maxes about 44C. The rear case fan varies with temps 800-1350rpms.

When finished, the outer plastic panels of the case will be covered with oak panels.

I'll have a write-up of the whole thing when it's finished.....

FWIW....I paid $108 for the Zen.