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Ultra-Quiet Linux Boxes?

Posted by Cliff on from the sshhhh! dept.

Percival asks: "For both noise and power-consumption reasons, I would like to build a silent linux box (i.e: no hard drive, no CPU fan, no PS fan). In my case, I need the box to IP masquerade as well as serve small print jobs through samba, but I can see many uses for a silent linux box. I would like to learn how to build a linux bootdisk that would load everything necessary into a ramdisk. The bootdisk HOWTO is very helpful, but it does not really address building a permanent linux system on a floppy, being aimed at rescue and tool disk creation. (The particulars: 2.2v Pentium MMX CPU with large heat sink, small, low-power PS, floppy disk, motherboard, two NICs, HP LaserIIp). Would I be better-off going with a diskless system (I would rather not have to rely on another linux box to boot)? Is this a pipe dream? "

3 of 32 comments (clear)

  1. Why X86? by terry · · Score: 3
    With Linux ported to so many other processors and hardware arrangements you're not thinking in a proper way. Instead of asking how to make an X86 box without components that are essential to it's longevity, you should be looking at your goal and work backwards from there. Hell, you may even find out Linux is not your answer. (gasp!)

    I think Rebel.com has done an excellent job with the Netwinder. It's a small computer using a SA1100 StrongARM processor. It's the same processor used in the Empeg car audio player and can do what you want and much more. It not only runs Linux, but it was designed specifically for Linux. I had a chance to talk with them at Linux World and I can tell you they're a small shop full of good people.

    You may also look at the LART project being done in TuDelft, Netherlands. I don't think they're selling anything (yet?) but it's nice to see Linux on a small processor capable of some real power. I don't have a link handy, oops.

    Or, you could use a uCsimm. It's a port of Linux to the Dragonball microcontroller with integrated Ethernet. It all fits on a 30 pin simm complete with Flash. I consider that to be really cool. There are many more choices out there than plain ol' Linux on x86. Don't limit yourself.

  2. PicoBSD by Hard_Code · · Score: 3

    Wouldn't PicoBSD fit in here pretty well? PicoBSD can run a pretty feature-filled system from a floppy.

    http://www.freebsd.org/~picobsd/

    Also, I've heard PanaFlow fans are really quiet and nice. Check em out in section M of the catalogue at http://www.digikey.com

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  3. Start from the top by overshoot · · Score: 3

    First off, you will be better off with a non-x86 processor. Whether they suck in other ways or not, they absolutely suck juice. That said, there's a lot you can do.

    Step one: forget the floppy and use a cheap CD-rom drive. They're made to shut down nicely and that way you won't be counting bytes.

    Step two: get rid of the heat generation. Use an old-but-not-ancient CPU on a motherboard somwhat newer than it is, with a selection for supply voltages lower than the rated voltage for the CPU. Processor power is proportional to the square of supply voltage and proportional to the frequency, so a reduction from 2.3 to 2.1 volts and from 233 MHz to 200 will result in a 30% power savings. The lower voltage won't support full speed, but will support a derated speed. You'll need to experiment with power, temperature, and clock multipliers. This is like overclocking in reverse; take the speed down (let's say from 233 to 166) and find out where the processor fails at 70C ambient. Put the voltage up a notch and drop the speed to 133 or less. That kind of thing.

    Finally, you'll want to slow down the fan. Notice I didn't say 'stop'. Fan noise is amazingly nonlinear. Drop the speed by half and you won't be able to hear it. You can drop the speed by using a lower power supply voltage than design; most fans seem to run on the +12v supply. Try the 5v supply and see if it starts reliably. Alternately, see if you can get a 24 v fan and run it at 12 v. Either way, the speed will be about half of normal, which translates into better than a 10 dB noise reduction. Put the fan behind a baffle and if it's not silent it'll be very close.

    I'd be very nervous about shutting the fan down entirely unless the PS is made to work that way (Apple was seriously anti-fan for years) because even in idle there are parts in the power supply itself that dissipate quite a bit of power and depend on air to get rid of the heat. Maybe not a LOT of heat, but when you divide by zero airflow the result ain't pretty.

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