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Quiet Cooling With a Copper Foam Heatsink
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.
And you can keep the pots and pans clean!
... for a dust free room!
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.
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.
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.
"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.
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A computer case that doubles as the heat-sink FTW!
http://www.quietpc.com/tnn500a...
Life is not for the lazy.
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.
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...
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.
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.
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