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Hardware Technology

Quiet Cooling With a Copper Foam Heatsink 171

Zothecula writes: The Silent Power PC is claimed to be the first high-end PC able to ditch noisy electric fans in favor of fully passive cooling. In place of a conventional fan, the unit uses an open-air metal foam heatsink that boasts an enormous surface area thanks to the open-weave copper filaments of which it's composed. The Silent Power creators claim that the circulation of air through the foam is so efficient in dissipating heat that the exterior surface temperature never rises above 50 C (122 F) in normal use.
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Quiet Cooling With a Copper Foam Heatsink

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  • by boristdog ( 133725 ) on Wednesday July 30, 2014 @01:18PM (#47567649)

    And you can keep the pots and pans clean!

  • Better have windows 9 when it comes out.

  • Perfect (Score:5, Insightful)

    by sammyo ( 166904 ) on Wednesday July 30, 2014 @01:24PM (#47567711) Journal

    ... for a dust free room!

    • Re:Perfect (Score:5, Interesting)

      by MDMurphy ( 208495 ) on Wednesday July 30, 2014 @01:40PM (#47567877)

      Dirt and dust is what I thought of also. While no moving air will help in that it won't draw as much air through it as a filter might, it will still collect lots of dust in hard to clean areas.

      The only thought I had, which seems impractical, is to be able to remove the heatsink and place it in a ultrasonic cleaning bath like those used for jewelery. I could see it as an interesting curiosity, one I wouldn't mind cleaning once a year so so if it were on display. But I can't see it being a practical alternative for home use.

      If it's very efficient maybe there's a benefit on putting them on rack-mounted servers that have cool, clean, air blown through them. Might decrease the density of servers you can put in a rack though, so there'd have to be a pretty good efficiency gain over active cooling to make that worthwhile.

      • Re:Perfect (Score:4, Insightful)

        by Ravaldy ( 2621787 ) on Wednesday July 30, 2014 @02:10PM (#47568147)

        Cleaning it will only be a problem if the product is soft. If it can support being hit with 90PSI air without bending at all it will be easy to clean. Depending on the type of copper used it should sustain 90PSI very easily.

        • Re:Perfect (Score:4, Informative)

          by v1 ( 525388 ) on Wednesday July 30, 2014 @05:51PM (#47570191) Homepage Journal

          Cleaning it will only be a problem if the product is soft. If it can support being hit with 90PSI air without bending at all it will be easy to clean. Depending on the type of copper used it should sustain 90PSI very easily.

          The hardness of the structure can be many times lower than the hardness of the material when you're talking turning it into FOAM. Compare the hardness of steel wool and steel.

          If this is anything like I'm envisioning, you could probably take a 3" block of the stuff and step on it and crush it down to about 1/4-1/8". And unlike traditional material foam, this stuff isn't going to spring back.

          Even if it can survive the blast of air, it may just serve to drive the particles deeper into the block. A filter has to be thin or very porous to insure air pressure can drive most of the trapped materials out.

          I'm betting the best way to deal with dust/dirt in this case is to simply filter the air very well. Very fine dust should be removable with air, but you don't want anything at or above large dust particle size getting into that foam or you'll never get it out.

      • could you put a static charge into the heat sink so it repels dust particles?
      • Re:Perfect (Score:4, Funny)

        by Anonymous Coward on Wednesday July 30, 2014 @03:20PM (#47568807)

        Maybe they should add a fan to blow the dust out.

      • by tlhIngan ( 30335 )

        You need to move air through it. Otherwise you know what you get? An insulator!

        Tiny pockets of air are very good insulators - it's why you use stuff like spray foam, fiberglass, etc., in your house - the material itself doesn't matter. The fact that the material traps air in tiny pockets makes it very insulating. Aerogel is one of the best insulators around - and it consists of basically air and a tiny silica weave to trap it in little pockets.

        This thing does have copper so it will transmit heat, but the ai

        • Looking at it the holes are big enough that I think that the heat entering the system will create the flow of air necessary to move the heat out. Hot air will rise out of the heat sink pulling cooler air in from the sides. Might work with no fan.
        • Insulating foams are usually closed cell foams because that traps the air. Flowing air would kill the insulation.
          In this foam the cells are far from closed. They are designed to be as open as possible. In that case there is flow, and a lot of it. What matters next is the surface area to dump heat through. Open foam has a lot of surface area.

          The material does matter. Copper is still a good conductor, while most insulating materials are made of plastics. Plastics are already quite decent thermal insulators.


    • Re:Perfect (Score:5, Informative)

      by jiriw ( 444695 ) on Wednesday July 30, 2014 @02:55PM (#47568557) Homepage

      Implicit question answered here []. For the tl;dr & tl;dt folk: Use a vacuum cleaner.

      Vor Staub braucht man keine Angst haben, denn durch den inneren Wärmepuffer kann Staub nicht bis ins innerste vordringen. Staub im äußeren Bereich lässt sich dank der Offenporigkeit leicht mit einem Staubsauger absaugen. Weil der SilentPower keinen Lüfter hat, wird Staub auch nicht wie bei normalen Computern angesaugt. Du wirst sehen, dass man ihn seltener entstauben muss als einen normalen Desktop-PC. Dennoch gilt das selbe wie bei allen PCs: Regelmäßiges Entstauben schont die Hardware.

  • by Selur ( 2745445 ) on Wednesday July 30, 2014 @01:26PM (#47567737)

    How stable is that foam and how good will it conduct heat once it gets squished by my cat/children/me accidentally putting a bottle/glas on it?
    -> without some kind of protection cage this seems kind of a bad idea,..

    • Re: (Score:2, Insightful)

      by Khyber ( 864651 )

      "without some kind of protection cage this seems kind of a bad idea"

      Good thing you're not en engineer and design person, then.

      Guess what typically surround metal heat sinks?

      Protection cages, like computer cases, amplifier cases, etc.

      What're you even doing on here if you can't think of something like that?

    • -> without some kind of protection cage this seems kind of a bad idea,..

      You mean like a PC case?

  • 500? (Score:4, Interesting)

    by hooiberg ( 1789158 ) on Wednesday July 30, 2014 @01:26PM (#47567741)
    This factor of 500 is a strange number. The copper fins of my CPU-heatsink also have a quite a large total area. A claim of two orders of magnitude needs a bit more justification than just a mention. Otherwise is just seems like a movie title.
    • by geekoid ( 135745 )

      It's has a tremendous surface area. For more then you fins.
      For comparison, then on the surface area of a brick cs the surface area of a sponge.

    • They are using the entire case as a heat sink, both the GPU and CPU are mounted directly to the top of the case. The foam is a gimmick, it would probably work just as well with fins.
      This will likely make upgrades difficult/impossible.

  • Kickstarter warning (Score:5, Informative)

    by Anonymous Coward on Wednesday July 30, 2014 @01:27PM (#47567745)

    This is not a real product. It's just being crowdfunded. The only evidence that it works is a claim by the creators that "the exterior surface temperature never rises above 50 C (122 F) in normal use", without specifying what "normal use" is.

    It might work and if so, great! I can't trust this article at this moment, however.

    • "Normal use" is likely a low wattage processor sitting at 99% idle.
    • by Lazere ( 2809091 )
      Wait... I must not have read well enough. Surface temperature? As in, the temperature of the heat sink itself? No mention of CPU temperature? That thing must be boiling under "normal use".
    • And you still need a fan even if it works, just not as large. Something needs to create an air flow within the chassis.

      • For silence you do need a large fan (or no fan). SilentPC's goal is to make silent PC's and that means no small fans rotating at high speed but big fans rotating leisurely.
        Or no fans at all. Convection can be quite strong if you build the thing as a chimney.

    • *Exterior* temperature? My current heatsink can manage a CPU temperature below that, with the fan at idle. Why would I want to downgrade to this thing?

  • Funding is sought via donations

    Because they don't seek to make a profit? because a charitable thing to do is create computer heat-sinks for the poor abused computers???

    Seriously what the fuck are they doing asking for 'donations'.

    Per-orders, fair enough, but donations should go to good causes, not £%^£"$£%^ing fancy PC heat-sinks.

    • by pla ( 258480 )
      Per-orders, fair enough, but donations should go to good causes, not ã%^ã"$ã%^ing fancy PC heat-sinks.

      You realize, of course, that Kickstarter exists to do nothing more than manage donations, a great many of which go to some variety of bleeping fancy PC toys?
      • by MrL0G1C ( 867445 )

        Except you usually get one of those fancy toys for your money. I backed a rear-light with integrated bike-cam on Kickstarter and the product I got was well worth the money.

        If someones giving money to Kickstarter to make fancy toys that other people will buy and the creators will profit from but then don't get one of those toys then either they're unbelievable stupid, vastly wealthy or somewhere inbetween.

  • by macromorgan ( 2020426 ) on Wednesday July 30, 2014 @01:28PM (#47567759)
    Will this "copper wool" be as flammable as steel wool? If so, that could spell trouble.
    • by jones_supa ( 887896 ) on Wednesday July 30, 2014 @02:10PM (#47568151)
      I'm sure the engineers have taken care of that problem. As a matter of fact, I'm just testing the product and...oh shit, my shirt is on fire...
    • I was expecting to be be far bulkier than steel wool, but that is basically just copper wool.
    • It looks like the burning of steel wool is basically just a corrosion based chemical reaction that is seriously sped up and self sustained by the heat. So, no, most likely copper is immune.
      • Copper corrodes fast when the temperature is raised.
        At my old job we worked with copper coated strip at 310 C. If you turned the N2 protection gas over the oven off the damn thing would turn black in seconds. Corroded.

        I don't know what it'll do at higher temperatures but at 310 C it corroded fast.

    • by Horshu ( 2754893 )
      Shouldn't be, which is one of the reasons that crackheads like to use Chore Boy for filters.
      • Now I'm wondering if we've entered the era when crackheads are more technically competent than the average Slashdotter...

    • Will this "copper wool" be as flammable as steel wool? If so, that could spell trouble.

      No. This is much less fine than steel wool: try burning a steel scourer. Second, copper is substantially less reactive than iron.

  • Old news. (Score:5, Informative)

    by ledow ( 319597 ) on Wednesday July 30, 2014 @01:30PM (#47567783) Homepage

    Bought a no-moving-parts power supply back in... oh, I don't know, 2003 or something. Sold as "cooled by heatpipes", pretty much the same principle - silent, no moving parts, passively cooled, no fans, huge surface areas.

    They also did kits for the processor itself but I've also bought P2-era motherboards that were designed to be passively cooled too (same thing, huge heatsink, no fan).

    So this is certainly not "the first" in the PC world (unless we're talking about "the first" to use some particular technology that just about replicates what I bought over 10 years ago). Not even close. In fact, it's over a decade out. And going outside the PC world, passively cooled chips are pretty common - you have a tablet or smartphone without a huge stonking fan, no?

    The PSU is still working 10 years on if you'd like me to dig it out. I'm sure it wouldn't take much to butcher it to do the same job to the processor, especially if you can safely have it clock itself down to prevent heat being generated in the first place.

    • Heat pipes are a little different as they rely on a phase change of some internal liquid.
    • Not even close to the first. I remember reading a review in PC Gamer magazine over 10 years ago about a fanless silent gaming pc.
  • that under """normal""" use don't reach 50c without a fan

    also, they are not the first to think about this. back in the athlon xp days i thought of a "hairbrush" like heatsink with many tiny copper strands
    however, heat transfer from sink base to each "fiber" is relatively weak

  • by nullchar ( 446050 ) on Wednesday July 30, 2014 @01:35PM (#47567835)

    I would rather have a normal heatsink (in popular form factors) for CPU and GPU out of this material. You would still want airflow through your case, or even on top of the heatsink, but RPMs of those fans would hopefully be much lower, making much less noise.

    Silent is a noble goal, but I would be happy to use standard cases and components being very quiet.

  • Could this be used for laptops, and maybe tablets and phones?

    I would think so. Laptops already have vents. A smaller, slower, quieter fan may be necessary.

    Surface area, it is why I prefer crushed ice on a hot day.

  • I am skeptical (Score:4, Insightful)

    by Solandri ( 704621 ) on Wednesday July 30, 2014 @01:41PM (#47567887)
    Assuming the copper filaments are cylindrical in shape, that's a surface area to volume ratio of (2pi*r*l) / (pi*r^2*l) = 2/r.

    OTOH, in a copper fin configuration, the ratio of surface area to volume is (2lw) / (lwt) = 2/t.

    In other words, if you use the same volume of copper and the thickness of the fin is half the diameter of the sponge cylinders, you have the exact same surface area. The thinner fins may be weaker, but since the additional fin material on the sides reinforces the structural strength, I assume that's not too big a deal. Just place thicker (stronger) fins along the outsides and you have a structure which is much more solid than the sponge.

    Now consider that in passive cooling the airflow is slow enough to be laminar. The flat surface of the fins (oriented vertically) will then impose less aerodynamic resistance, leading to higher flowrate, and thus greater heat exchange.

    Unless there's something else going on here (maybe the sponge filaments are wrinkled instead of smooth), or it's that much harder to make thin fins than spongy cylinders, I don't see how this could be better than a traditional fin-type heatsink.
    • In other words, if you use the same volume of copper and the thickness of the fin is half the diameter of the sponge cylinders, you have the exact same surface area. The thinner fins may be weaker, but since the additional fin material on the sides reinforces the structural strength, I assume that's not too big a deal.

      I agree with the rest of your argument, especially including the fluid flow part. However, I'm not sure if this part works out, it really depends on other assumptions. For a point load I agree -- the load is spread across the width, at least to some extent. But with a wider surface, you generally experience more load, proportional to the size, and there's no benefit in connecting the fin segment to neighbouring segments. So the cylinder would be stronger in this sense. It's the intuitive idea of increasing

  • Efficient? (Score:5, Insightful)

    by msauve ( 701917 ) on Wednesday July 30, 2014 @01:44PM (#47567921)
    "the foam is so efficient in dissipating heat that the exterior surface temperature never rises above 50 C (122 F) in normal use."

    Hey, I can glue a chunk of styrofoam on a CPU, and the outside of it won't even get that hot. I wouldn't use that fact to claim that styrofoam makes a great heatsink, though. Quite the opposite.
    • I was about to say basically the same thing - the interesting number on a heat sink is how cool it keeps the heat *source*, not the coldest outer edges of the heat sink.

    • According to some tests I did a while ago with conventional passive heatsinks, if the exterior surface of the heatsink is reaching 50C that means that the processor below is getting much hotter than 50C. Big trouble.
  • by DigiShaman ( 671371 ) on Wednesday July 30, 2014 @01:51PM (#47567971) Homepage

    A computer case that doubles as the heat-sink FTW! []

    • A computer case that doubles as the heat-sink FTW!

      At 70 lbs, it could also double as a boat anchor.
      Increasing surface area of your heat sink is a much more efficient way to dump heat than increasing the thermal mass of your heat sink.

      • by Gryle ( 933382 )
        The added weight is an anti-theft measure. This way the thief leaves your desktop alone in favor of your more expensive and more easily portable television!
    • Oh my... And I thinking that diving the computer in oil was bizarre.
      • It still is. The physics of oil cooling is good, but it's not practical in terms of the effort it takes to both administer and replace/upgrade hardware. If left in an enclosed system like power transformer, sure. But then again, those are mainly "set it and forget it" devices rarely touched once in place.

    • I love how the page sells it as "Developed using heatpipe technology to create a 100% passively cooled environment," right above a picture of the back of the case, which features,

      wait for it...

      A fan mount!

      Gives me a chuckle.

  • by gman003 ( 1693318 ) on Wednesday July 30, 2014 @01:56PM (#47568037)

    It's using a Core i7-4785T, an "ultra-low power" processor (shown by the T suffix - S indicates a "low-power" part, and K indicating an overclockable part). This particular one is a 35W part running at only 2.2GHz, while the regular i7-4790 runs at 3.6GHz (and 84W)[citation] []. Turbo boost can bring that up to 3.2GHz on a single core (on the regular chip, 4.0GHz). So the CPU is not a regular desktop chip at all, let alone a "high-end" one.

    The Nvidia GeForce 760 is a bit of an interesting choice. It's not powerful enough to be called "high-end" (I would apply that label only to the 780 and 780 Ti of that series), but it doesn't fit with the ultra-low power CPU. If they were thermally constrained (as their CPU choice indicates), I would have expected to see the 750 Ti - not too much weaker (~30% [citation] []), but with a far lower power draw (it's the most powerful card to be powered only by PCIe, no extra power connections needed). Seriously, the 760 is a 170W card, and the 750 Ti is a 60W card. Seeing how they handicapped the CPU to shave off 50W, I don't see their logic for not shaving 110W for a similar performance penalty.

    Because of their choice of CPU, I can't really support their claim of being a high-end desktop with passive cooling. They are much more powerful than most fanless PCs, but most fanless PCs are also designed for industrial use, not for regular office/home environment. So it's an improvement, but not a revolutionary one.

  • It's a Brillo Pad?
  • Hmmm... (Score:5, Insightful)

    by fuzzyfuzzyfungus ( 1223518 ) on Wednesday July 30, 2014 @02:47PM (#47568467) Journal
    With finned heat sinks, one of the limits on size was that the comparatively low conductivity of the fin material made surface area increasingly unhelpful as you got further from the heat source. Especially with paper-thin lightweight aluminum you could just keep making them bigger; but much of the fin would be essentially wasted because the delta-T between the more distant areas of fin and the source of the heat would be so high. Plenty of heat exchange surface; but not much heat making it out that far.

    This is why more or less all contemporary heatsinks started embedding heatpipes some time ago, since that was the only way to get a reasonable amount of heat to the more distant parts of the heatsink.

    This 'sponge' is more aesthetically interesting; but I see a lot of surface area that is only tenuously connected to the actual heat source. Newer Intel silicon just doesn't pump out the watts the way the old stuff did, so it might actually work; but I'd be shocked it if works any better than a much more prosaic heatpipe-and-fins design.
    • by Twinbee ( 767046 )
      What you say seems to imply that the best design for a heatsink is a 3D fractal of some kind, where a big chunk of metal splits off into smaller chunks which themselves split off.
      • Theoretically, probably, yes.
        However, the efficiency will probably just not look good enough once you see what you have to pay for it.

        This same foam structure but with some trick causing thicker strands at the bottom would be a nice approximation.
        Perhaps it is possible to centrifuge the thing before cooling the copper? Copper would flow over the strands to the bottom side, thus the bottom would have thicker strands.

    • I agree that this doesn't pass the sniff test. A foam has a low ratio of metal to air, it's the cross-sectional area of the copper that allow vertical conduction of the heat from the heat spreader plate. This has little copper area so conduction is limited. It's further worsened by the random nature of the strands so the heat is conducted laterally as well as vertically and so the conductive thermal resistance is increased because the heat needs to travel a longer path.

      So while I'm not saying it doesn't

  • I had recently upgraded the CPU in my living-room MythTV PC to an i7, using the standard Intel fan cooler from the retail box CPU. (It originally had the lowest i3 Celeron I could get, because I wasn't sure I would finish it.) The PC itself was in an Antec quiet case which generated little noise.

    Upon waking from a nap on the couch, I heard the sound of a fan and thought that it was coming from the PC. Once I had fully awakened, I realized that the noise was actually coming from the main air intake to the c

  • Aerogel (Score:3, Insightful)

    by rudojob ( 1754140 ) on Wednesday July 30, 2014 @03:10PM (#47568695)
    Somewhat surprising. This reminded me of a metal aerogel and aerogels are good insulators []
  • Reynolds number (Score:5, Interesting)

    by TeknoHog ( 164938 ) on Wednesday July 30, 2014 @03:27PM (#47568877) Homepage Journal

    basically means that for slower airflow, you need larger gaps for air to flow through. This is why the sponge is bad for heat dissipation, and great for insulation. It's kind of intuitive, but it's nice to have some science backing to it. Having a large surface is good, but it doesn't help if the airflow across the surface is limited.

    On a side note, I've been on a quest for quiet cooling since the very early 2000s, incidentally after getting a physics degree. It's mostly in the last couple of years that I've started to see really sensible coolers in the general market. For example, the usual CPU cooler in the olden days had a fan pushing right against the CPU with minimal fins in between, meaning there's a considerable high-pressure centre with no airflow. No one with a fluid mechanics 101 would design crap like that. OTOH, the traditional CPU/mobo setting is a little problematic; first you put the most heat-concentrating element in the middle of everything, and then later you realize it needs cooling. (I'd put the CPU socket on the reverse side and use the case as a huge heatsink...) Now finally the designers have the sense of using a straight sideways airflow, combined with heat pipes. Why the fsck did this take so long?

    I used to strive for pure passive cooling, but in the end I don't mind a large, slow fan -- it's enormously better than no fan, and still indistinguishable from other background noises. This is another nice thing to see in cooler designs, from the 1-inch whiner in my first Linux laptop to the 140-mm quiet giants that can easily manage a couple of hundred watts of GPU.

    BTW, if you ever need to explain somebody how a heat pipe works, take them to a sauna.

    • OTOH, the traditional CPU/mobo setting is a little problematic; first you put the most heat-concentrating element in the middle of everything, and then later you realize it needs cooling.

      The theory is that the exhaust air from the CPU heatsink spreads out to parts that are more heat-tolerant but still need active cooling, such as the voltage regulators. A VRM that can operate at 100C without trouble can be cooled just fine with a slow flow of 50C exhaust air from the CPU cooling system.

      In practice, people

  • Would anyone here doubt that a Mac Pro is a 'high end machine,' or that the posted specs for system noise don't make that "quiet?

    One difference is obvious, you can go see, listen to, and buy a Mac Pro right now.

    • The mac pro* is quiet, but it isn't actually silent. It's close, but there's still a fan in there. You just can't see it clearly - it's on the bottom.

      *I assume you mean the flower vase model.

  • Their copper "foam" reminds me strongly of the brass "sponge" that I use to clean the tips of my soldering irons. I wonder if there's a DIY cooling project I've been missing?

  • Does anyone actually care about fan noise? The only reason to ever think about forgoing fans, imho, is dust. If you can seal a case from the outside world, great. You would have a lot less trouble down the line.
  • What a neat looking dust filter. Probably will do a good job catching cat hairs too.

  • How does such a system deal with the inevitable dust that gets inside a PC? Fans can be cleaned but how does one deal with this copper mesh?

"Well, it don't make the sun shine, but at least it don't deepen the shit." -- Straiter Empy, in _Riddley_Walker_ by Russell Hoban