Remote Cooling

or “How to route cooling air from a remote location to a computer located inside of an entertainment center and significantly reduce system noise at the same time.” – biyonic2000

or….

Quiet computers are all the rage as our PC’s move closer and closer to our home media centers. Following this trend, I put my main computer into a built-in entertainment center. In doing so, the ventilation was cut to zero and case and CPU temperatures immediately rose to hazardous levels. I had to use the computer with the door of the hutch wide open for air circulation and that was loud and impractical.

The first workaround was to put a 12V fan into the side of the hutch wired to the motherboard. This worked for basic exhaust but introduced noise. In addition, I’m overclocking, so I definitely need an abundance of cool air.

Therefore, to get some cooler air, I decided to drill through the floor of the hutch directly down into the joist space of my unfinished basement. By ducting roughly 3 feet from the basement to the hutch, I could get a year-round constant 68 ºF air to my computer. I drilled and cut a 3 inch diameter hole to accept aluminum flex duct – $4 from Home Depot

Selecting a Fan:

The best fan to use would be a squirrel cage blower. But this type of blower is expensive and noisy by design. I tried an AC computer style fan from Radio Shack ($20) and it was very quiet but was not really powerful enough to overcome the resistance in the duct. Next I tried a 6″ AC duct booster fan from Home Depot ($20) and it was surprisingly underpowered and noisy. I quickly came to the conclusion that using AC voltage would introduce a chance of shock and wiring/fire code issues – definitely not worth the hassle.

Frustrated and out of options, I built a mock up fan enclosure out of a cardboard box. I put three small 12V computer case fans wired in parallel onto the box and left a 3 inch hole open. I secured the duct and my test run surprised me with the results. Three little 80mm 12V DC axial fans produce some decent pressure at the exit end of the duct!

See below for the final design:

It’s not rocket science to build an enclosure out of Tupperware, sheet metal or cardboard. Just make sure to leave room to add a filter of your choosing. For my filter, I used a cheap cut-to-fit air conditioner filter held on with a rubber band. Anything else – like an auto air filter – would be too restrictive.
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biyonic2000

The duct enters the case through the side right over the processor heat sink/fan. I used a disk of sticky back foam to create a sleeve/socket in which to slip fit the end of the duct into the case. It is a great way to easily secure an airtight seal while allowing some play in the duct to occur.

The computer case is sealed with foil-type duct tape to ensure positive pressure with only the PSU fan venting spent air out of the case. After the spent air leaves the case, it exits the hutch enclosure at the opening that used to have a fan in it (note rectangular opening just to the left of the keyboard tray):

Powering the Fans:

For wiring and power to the remote fans, I installed a black and red pole speaker terminal (Radio Shack) in the rear of the case. The speaker terminal is powered by the DC wires of one of the hard drive-type power connectors from the PSU. This allows the wires coming from the remote fans to the computer to be easily removed/connected without having to open the case. Powering the fans from the power supply ensures that the fans will start and shut down in sync with the computer.

Results:

With my remote air handling unit running, the BIOS temp monitor reported a steady 20 – 25 ºC case temp with the CPU at 41.5 – 45 ºC at load. Noise has been reduced to a whisper, if that. Hopefully this article will help you get some ideas for your air cooling project. If you have any questions you may email me.

biyonic2000