Slashdot Mirror

← Back to Stories (view on slashdot.org)

Quiet PCs, Ducting Air from Case Fan to Heatsink?

Posted by Cliff on from the the-ever-lasting-quest-for-quiet-computing dept.

Milo_Mindbender asks: "While listening to the whine of my heatsink fan I was wondering. It seems like a good way to get quiet cooling for the CPU would be to mount a fan in the back of my case and run a duct of some kind (folded sheet metal or some kind of hose) from the back of the fan directly onto the top of a fan-less CPU heatsink. You should be able to get the same amount of airflow with a large slow (quiet) case fan as you do with a little noisy cpu fan...and the air being blown onto the heatsink would be cooler as well. This seems like a fairly obvious idea so I'm wondering if there's some reason why it wouldn't work, or if anyone has tried it and could tell us how it turned out." Yeah, but what about the heat in the rest of the system? Depending on the size of your enclosure (and what's in it), you may or may not need more than one fan. Has anyone tried something like this and can comment on how well it worked?

12 of 105 comments (clear)

  1. Google says by Anonymous Coward · · Score: 2, Informative

    Ducts - The Cheap Cooling Solution

    Didn't work too well until there were 5 fans in the side of the case,

  2. Altenateively by brejc8 · · Score: 1, Informative

    You could make a better designed processor which works harder at not computing pointlessly.

    A high speed x86 cpu wastes 90% of its power on operations who's result is thrown away.

    Clock gating and whipping engineers is just two stratergies.

    --
    Mouse powered Chips, Open source Processors and Lego
  3. Already been done by waytoomuchcoffee · · Score: 4, Informative

    link

  4. Dell did this by bartb · · Score: 4, Informative

    I have two dell PCs, the first is 4 years old, the second 2 years. They both use a plactic duct that is attached to a fan in the back and covers the CPU entirely.
    The four year old is still really quiet, the other one is starting to make more noise. But that's because of a buggy fan on the video card...
    -> maybe we can apply the same strategy there?.

    1. Re:Dell did this by thogard · · Score: 2, Informative

      Static from the high speed air flows you get from compressed air can kill electronics. Don't do this on a day when your going to get zapped everytime you touch a door knob. A good rainy day is best.

    2. Re:Dell did this by Tom+Davies · · Score: 2, Informative

      You can often quiet an older fan by removing the sticker which covers the bearing and putting a drop of oil (sewing machine oil or car engine oil) on it.

      Tom

      --
      I have discovered a wonderful .sig, but 120 characters is too small to contain it.
  5. I just got a system that works like that by foonf · · Score: 3, Informative

    Its kind of old, a FIC Neptune mini-NLX system. If you are at all familiar with the NLX chassis layout, the CPU is placed in the upper right corner of the motherboard, directly in front of the front case fan. There is a small duct focusing the fan on the CPU, and as there isn't even a place to plug a CPU-mounted fan in, you have to use a passive cooler and hope the case fan is sufficient. It was designed for Pentium II and first-generation celeron systems, apparently the motherboard can run coppermines though...so far, with a slow celeron, its been fine with no CPU fan.

    --

    "(Man) tries to live his own life as if he were telling a story. But you have to choose: live or tell." --Sartre
  6. As a matter of fact... by consoneo · · Score: 2, Informative

    I have seen that some Compaq machines use this method. I haven't seen them have any problems with heat, or noise. Your idea has been thought of and put into effect long before you thought of it. :) Good going. (This happens to me a lot!)

  7. 60 - 80mm adapter by aliusblank · · Score: 1, Informative

    While what your suggesting would work, a better solution would be to get a 60 to 80mm fan adapter for the heatsink
    and use a low noise panaflow or sunnon 80mm fan. While a bit more expenisve, this should keep the system cooler
    and have an equal or lower noise level.

  8. Too many bends in air hose by Anonymous Coward · · Score: 1, Informative

    In almost any setup, there are a handful of bends in the air hose.

    Each 90-degree bend in an air hose is the same airflow change as extending the hose 5 feet.

    You'll get some pretty bad, expensive cooling.

  9. Re:Problem and solution by PacoTaco · · Score: 2, Informative
    You should also consider an acoustic dampening case like the Silent PC Pro S. I have one of these and it's absolutely silent. The case has foam layer to reduce noise, great airflow and a 20 db power supply. It's also solidly built, which greatly reduces vibration. There's no internal ductwork, so you can install whatever you want without any issues. These cases run around $150 and are tough to find, but well worth it in my opinion.

    If your hard drive is bothering you, I suggest a Fujitsu MPG-AT drive. Fujitsu uses liquid ball bearings which eliminate that annoying whine.

  10. TMTOWTDI by Etyenne · · Score: 3, Informative

    Brand name computer maker (Dell, IBM, Compaq, etc.) do that on many model of business class PC.

    You may not know, but there is a whole culture that had developped around cooling and case modification. People do air duct all the time out of cardboard, soft metal, acrylic, etc. There are many other option : mounting a larger fan right on your HS with an adapter, throttling your fan down (7volting, rheostat, voltage regulator [my favorite], PWM), using a quieter fan (Panaflo L1A are popular), etc. Check out the Case and Cooling Fetish forum of Arstechnica. 7 volts is another site I like very much.

    --
    :wq