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Ultra-Quiet Linux Boxes? 32

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? "
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Ultra-Quiet Linux Boxes?

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  • The last computer I saw without a fan had vacuum tubes in it, heh.
  • If you do this then it should not be a problem espescially if you only use an old laptop drive that will be both low power and noise. see my website for a do-it-yourself power supply this one does 100W with no fan off a 12v battery my orientation is for a car player but you can probably get away with an LCD like I use as well. cya, Andrew...
  • by terry ( 89685 ) on Thursday November 11, 1999 @09:49PM (#1540302)
    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 [rebel.com] has done an excellent job with the Netwinder [rebel.com]. It's a small computer using a SA1100 StrongARM processor. It's the same processor used in the Empeg car audio player [empeg.com] 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 [uclinux.org]. 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.

  • by Anonymous Coward
    I agree it'd probably be simpler to just have it boot from a small hard disk (pick up an old 540Mb one or something) and if it wasn't used, it would power down. If you're going to run in RAM anyway, then disable swapping to make sure it stays 'asleep'. What kind of load will this system have? A lot of 486's never had fans on them, if the speed decrease wouldn't kill you. I'm trying to think stock solutions here, rather than having to purchase anything exotic or expensive, but perhaps one exception could be made: A peltier(thermoelectric-no moving parts) cooler for the CPU if oversized heat sinks and enhanced heat convenction (perhaps through modifying the case to be more open)wouldn't keep things sufficiently cool by themselves.
  • Thinking about it, just take out the PSU fan, if your PSU is rated high enough and you have a low load then it should be ok. Just keep an eye on it in summer.

    cya, Andrew...

    PS:when it blows up don't complain ;)
  • Open the power supply and put a ~20-40 ohm 5W (or less) resistor in series with the fan. The fan will still work but it will be silent.

    I have a linux home server running 24/7 like that and I've had no problems.
  • So this works how? By slowing the RPM of the fan?
  • I bought an ultra-quiet power supply from PC Power and Cooling [pcpowercooling.com] and it was, in fact, totally silent. It's fan is so quiet that sitting in my office I could not hear it running. I could hear the hard disk, but when it spun down (power savings) the box sounded like it was off.

    They make very quiet CPU fans as well.

    A while ago, I saw some solid state disks packaged just like the regular spinning kind, but built with NVRAM or something like that. Very fast. Very expensive. Very quiet. Now that I think about it, probably very hot as well....

    There was a company called Ergo that used to make a system called 'the brick'. It was very small (for those days) and had no fan. The case was one big heatsink and they used a clever device to transfer the heat to the case. It looked like an anti static bag (size of one wall of the enclosure, about 3 mm thick) filled with some sort of heat conducting liquid.

    You can replace many 'fan required' situations with an oversized heatsink that has outside the case exposure, as long as it has good contact with the hot component. (don't forget the heat sink compound).

    Hmmmm maybe that would be a good oddball case direction, something that looks a bit like a porcupine, lots of external heatsink on the case itself....

  • You can get embedded power supplies that run at 70W and use free air cooling, I have seen them on sites that specialize in embeeded PC's.

    Also Compaq Deskpro's with 233Mhz pentiums just use a heatsink, so you should be able to make a completely silent machine if you don't have a disk.
  • If you use a diode instead you lower the voltage with a fixed amount no matter how much current your fan uses. I have slowed down my PSU fan using this method (reduced voltage by ~2.25V - think it is a zener-diode). Make sure to mount it in the right direction!
  • Netwinders were cool when they first came out, but overpriced. They're still overpriced, but now the coolness factor has worn off.

    The fact that they only have 2MB of video RAM and can't use an add-on video card makes them unattractive as a desktop machine. The high price makes them unattractive as home server. I don't manage any rack mounted computers, so I can't comment on whether the small size is a big enough deal to overcome the CPU and RAM limitations.
  • They just use a heatsink on the CPU daughter card because there's a big fan in the rear of the case pointed at it. Still a CPU fan, just not directly attached.
  • by cr0sh ( 43134 )
    You have defined what you want (low noise, low power, no hard drive, no cpu fan, no power supply fan), but your reasoning behind what would make the machine silent is a little flawed. Let me elaborate:

    Removing all fans from such a machine - indeed, all moving parts - would make it silent, and use less power. However, in the quest of doing so, you will run into issues which begin to raise the cost of the system - such as what to use to boot the system. You indicate that booting with a floppy would be OK if you could get everything you needed on a floppy - so boot noise doesn't seem to be an issue. But running noise - that is, noise generated in normal operation of the machine - is an issue. Solid state disk devices would be the only option (unless you do get a full system on a floppy - which I can't say would be impossible) - and a very costly option.

    Running noise seems to be the issue here - the solution is to choose components that make as little noise as possible (until it is inaudible to a human), and will use as little power as possible. To this end, I offer this list:

    For the CPU - use an AMD 5X86 OC'd (or not) to 160 Mhz - these can be bought off of eBay or surplus very easy. Use a good 486 heat sink with fan, and compound to cool it. Most fans on 486 heat sinks are inaudible, especially in the case.

    Use a 2.5 inch laptop IDE hard drive to boot from. 100 Mb hard drives can be had off of eBay for 5-10 dollars, sometimes less. Wrap the hard drive in some egg-crate - with it inside the case, you won't hear a thing, and the drive won't heat up enough to worry about cooling it.

    For the power supply, we need to get creative - go to www.alltronics.com [alltronics.com] and order their Mini Switcher power supply (stock #98E011). You might want to wire up another Molex connector for the motherboard, as it comes with only a single connector (the one with 12V, -12V, 5V and ground. It doesn't output -5V. In fact, I don't think it is needed, as a machine I have runs fine without the -5V output. Anybody know what the -5V is used for in a PC?). It has 2 standard drive connectors, and one mini connector (for the floppy). I believe it outputs 60 watts without a fan, but add a fan (23 CFM), and output goes up to 80 watts. However, a 23 CFM fan might make too much noise to be comfortable for you - you might want to try smaller fan(s) - maybe 486 coolers, to get a little airflow over the thing (don't just box it up, give it some breathing room).

    Think about the area and the noise level the box will be used in. Silence is not being heard because of surrounding noise (it is easy to be "silent" outdoors - just don't make more noise than what is the ambient level outside) - and most rooms have a lot of ambient noise. You may want to get somebody to measure the avaerage dB level of noise in the room - just don't make the box emit more than this level, and the box will be silent.

    While what I described isn't "silent" by your definition - it is silent by normal definition - that is, it make so little noise you would be hard pressed to hear it. The loudest thing in this box is going to be the hard drive - and it will be damn quiet. I have built a box similar to this, for an in-vehicle computer system - I use all of the parts mentioned (well, my hard drive is larger - it is a 350 Mb), including the power supply. The hard drive is wrapped in egg crate, and doesn't get hot at all. Neither does the cpu (which is OC'd for playing MP3's). In total, I have spent maybe $50.00 on this system. It doesn't make any noise in a quiet room, and it is definitely inaudible in my vehicle.

    What you ask is possible, and easy to do, if you are willing bend your rules a little. Hope this helps...
  • Thermo-electrics, eh? Never heard of it, so I chased down a website (using the ever-amazing google [google.com]).

    The first match [tellurex.com] I found seemed to suggest that like brakes on elecric cars, these devices could transform heat to electricity. Conservation of energy means that in a laptop, this would cool while recharging the battery (Didn't look closely enough to see if there was a useful voltage, but still!).

    Lovely idea, no? Why spend precious energy on a fan, when you can just pump the heat back into the battery. Smile!
  • I have an old 386 with a 1.6 gig drive (which was big when I installed the drive, though the 386 was old then) that I boot several machines off of. This 386 sits in a corner where it cannot be seen or heard. I got a modem in there for masq (notd) work.

    Machines that are off make no noise, and I can live with a little noise when working. (Note if I was doing stuido music I couldn't live with noise)

    Suns boot great off of the network, since they were designed for that from day one. For PCs, most network cards have a socket for a boot prom, and I think there is a linux project to program them. (Check for a working prom before getting the card!) This way you don't even need a floppy, and the disks are in the basement/closet where you won't hear them. Not all 486s needed cooling fans, and they make good X servers for most people, if you can get a quiet power supply you are set.

    Anouther alternative is an old notebook. They were designed for low power, and heat = power. Either as an X server or a full blown linux system they are great. A bit more expensive and you have to be sure that linux works before buying.

  • by Hard_Code ( 49548 ) on Friday November 12, 1999 @09:17AM (#1540317)
    Wouldn't PicoBSD fit in here pretty well? PicoBSD can run a pretty feature-filled system from a floppy.


    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
  • If this worked, I'd say go all out on the laptop idea you mentioned. The problem is that you don't get something for nothing. Notice that to get the electric power generation you need a heat gradient. The problem is, for the kinds of temperatures we're talking about, where are you going to get that heat gradient? Answer that, and I'll tell you exactly how you want to cool your processor. You don't want the power generation side because you don't get something for nothing. You can't get enough room-air cooling on the other side of this thing to eliminate the heat and also generate any reasonable amount of power. That is, unless you put a fan on it, which is exactly what you wanted to get rid of! These things are also not what is used on electric cars (unless they changed something drastic yesterday)... it is usually something much simpler--a DC generator (read, DC motor) on the other side of the drive shaft with a load on it works as electric brakes. This is incredibly simple considering that you already have a DC motor on the other end of the driveshaft, and it's the same motor that makes the thing go in the first place. They use this in metro trains, nothing new.

    You know, have you ever noticed that a mouse is warmer after a tense person has been gripping it for any decent amount of time (if it's over an hour, it also has sweat on it)? Well why not get some extra energy from the heat? Before you go thinking, "Great idea(==money-making oppertunity!!!)", note that this is the same situation as above; what are you going to get the heat to transfer to so you can get the energy out of it? The mouse pad, if practical otherwise, is out of the question because you usually rest your wrist on it, and the wrist can get hotter than the palm. Anyway, it's not a very good heat-holding material, so it wouldn't absorb heat that readily.

    We're going to get a new heating system for my house, and I was just thinking that maybe I could try out one of those thermoelectric thingys in the heating mode and use it like a heat pump, except much more efficient. There has to be a reason that no one has done that, though. Still, I might want to try it; anyone out there got some money to contribute to a research fund?

    Rule #2,316: Never ask for money on Slashdot.

    Never mind. I just wonder if I'm breaking some other rule :-?.

    Don't get all hyped up; that was made up.

    <i am="Kenneth Arnold">Hi!</i>

    PS - I hope that "HTML" works--last time I tried that it got all messed up. When you preview ampersand-escaped stuff, the Comment text box has it un-ampersandized, so you have to re-ampersand it. Drives me insane. (So this is an experiment.) I'm just clicking Submit.

  • Don't forget that you can use 2 floppies, it is perfectly OK to use 2 3.5 floppies off the controller. Perhaps OS on one and utils on another. This would effectivly double your disk availiability. Hell, I remember years ago there were floppy controllers that would allow up to 4 floppies, if this is still availiable for 3.5" 1.44megs you would have quite a bit of space for a few options. Just a thought.
  • I'm not too big of a fan of mac's myself, but the new iMacs no longer have fans in them and supposedly run very quietly.
  • http://www.linuxdevices.com/files/eprom/eprom.html
    For cooling, use natural convection as much as you can by standing the machine upright (on it's side rather than horizontal.) Then make sure the cards at 90 deg to the board are vertical so air can easily pass by them. Also be sure to use lots of extended surfaces (fins - heat sinks......). This is a good start if you can't use fans.
    Good luck.
  • cr0sh asked:
    Anybody know what the -5V is used for in a PC?

    Sure. It's for the substrate bias on triple-supply (+12v, +5v, -5v) 16 kb DRAM chips. No, that's not a mistake; I really mean sixteen kilobits.
  • by overshoot ( 39700 ) on Friday November 12, 1999 @01:29PM (#1540323)
    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.
  • So is this something left over from the original IBM machines? To power the DRAM in it? Heh, all I know is that my machine works fine like it is, so I am not complaining...
  • Check out the Linux Router Project [linuxrouter.org]. What you get is a full Linux box with a router, BOOTP or DHCP or PPP, Apache, or anything at all that you can fit on a floppy. It loads everything into RAM, so you don't need a hard drive, and you wouldn't need a very powerful CPU for what you're doing.

    Silence is golden!

  • iMac's now don't have fans :-) If they don't run Linux yet, it will be soon - all the older rev's do, and the iBook does (so the new UMA mother boards work). It would be a silly choce for a hidden-away gateway they run Linux, of course.
  • Lowers the voltage driving the fan. The only thing that you have to worry about is that the fan can still start from a dead stop/power off. It needs more power to start.

    As per the other posters suggestion I would recomend a couple of diodes in series with the fan as you will have better control over the voltage. Ofcourse if all you have is a resitor use that

    If you wanted to be a real smart ass you could rectify the signal from the fan's tac and use that in conjuction with a transistor and maybe an amplifier to control the fan's speed more precisely.

  • Wow. What a great response. I think that my idea for this system is do-able. I appreciate the links to other systems, and I would definitely look at something like the Netwinder if I was into buying something new. I have two 386s and four 486s in various states of disassembly. I want to use them all. I also have a Pentium system to play with.

    After reading responses and webpages (and thinking), I have come to these conclusions:

    1) CD-ROM, why did I not think of this earlier? You can boot off it on most pentium motherboards and on almost anything if it is SCSI. Then, it'll power itself down, so if you load a ramdisk as root, you can pull as much info off the CD as you have RAM, and then forget about the CD until you have to re-boot.

    2) I was thinking about solid state. That would be the best of all worlds. Does anyone know about the existence of products (or the feasability of building such) to use large amounts of 30-pin SIMMs? I have MEGABYTES upon MEGABYTES of 30-pin SIMMs. If I could stuff more than eight onto a 486 motherboard, it might even serve a web-page or two (over a modem maybe). I would be worried about reliability.

    3) After looking to single and dual-disk linux distributions (there are about a dozen that I found), I have come to the conclusion that there is a HOWTO missing: "HOWTO Roll your own distribution." Maybe not a full-blown distro., but some information about creating a linux system from scratch, and adding things on a 'need-to-add' basis. The point would be to learn to create these single-disk, RAM-disk, CD-bootable, etc. mini-systems. With the surgence (is that a word?) of DSL, cable, and other broadband technologies in the home, there are many people out there who are running Win95 on a DSL with file and print sharing turned on. The ones I know end up pulling their plug (ethernet) when not online because there are no easy solutions. It seems to me that if people could learn how to create simple, small linux systems, it would be easier for everyone to put that old 486 in the front lines as 12-year-old hacker fodder. The mind wanders into web-based configuration and mainstream uses.

    4) The most difficult part - the power supply. This has given me the most to think about, and has presented the greatest difficulty to me, as I know next to nothing about electronics. I guess the only thing I can think of is: Do wires carrying electrical power (DC) suffer from length? Let me explain. If I wanted to do some recording - digital audio - and I wanted a silent room, I would not want to put my entire system out of the room, and run keyboard/mouse/video cables for 25 feet. How about running the powersupply outside of the room and running 25foot ground/DC wires? And SCSI can go for several feet, so you could get the drives a little farther away. Actually, I have not thought about trying to record directly to CD-R. Probably not so easy.

    Again, thank you all for the responses. I guess I have my work cut out for me here. I would love to begin writing a HOWTO on creating your own system/distro., but I do not have the expertise right now. Maybe I will when I have finished this quest.

    Off I go, like an ass in the desert to do my work (putting a resistor into my power supply and trying to create a CD-boot simple router system with, maybe a web-server on it - it'll be quieter than my hard drive, and it might work with 80MB of RAM).

    Benjamin McGough

Just go with the flow control, roll with the crunches, and, when you get a prompt, type like hell.