Fanless spinning heatsink - the new future of CPU cooling?

[SXRguyinMA]

:think:

http://news.cnet.com/8301-17938_105-20078781-1/fanless-heat-sink-design-promises-cooler-quieter-cpus/?part=rss&subj=news&tag=2547-1_3-0-20

[diluzio91]

The Sandia cooler could finally offer the cooling efficiency necessary to allow for processor clock speeds above the current rough 3.0GHz limit.

Yes... <_< >_>... 3GHZ....

[crenn]

Interesting, is this the new 'metal based' cooling solution? (I say this because we were told about a fantastic new heatsink based on liquid metals was going to revolutionise heatsinks.... as I recall, the product didn't do very well and didn't perform that great)

[x88x]

Color me skeptical. They do at least have an interesting theory, though.

BTW, a much better article on it here:
https://share.sandia.gov/news/resources/news_releases/cooler/
Also a whitepaper on the technology (PDF):
http://prod.sandia.gov/techlib/access-control.cgi/2010/100258.pdf

[NightrainSrt4]

Just looking at it, it seems like any benefit of stopping the dead air on typical fins would be lost by the heat transfer between the base plate and the spinning plate. And if they've found a way to transfer the heat between the two plates better than the cpu to a standard heatsink, that technology could just be used to improve the standard heatsink.

[TheGreatSatan]

^Exactly

[RogueOpportunist]

From my limited "enthusiast" knowledge on cooling I see nothing about the design that would suggest any serious airflow/cooling improvement over your typical stock CPU cooler but on the other side of the same coin I see TONS of flaws, notions and concepts that seem to be "wrong".

The idea that moving metal through air is going to cool more efficiently than moving air through metal seems "off" to say the least, plus putting a thin layer of air between the base plate and impeller seems like it would be counter productive.

Call me a realist but this looks more like someone trying to cash in on a patent than any kind of technological "advancement".

[crenn]

Unless you're a master of thermo dynamics and fluid dynamics, I'd read the paper in full before you judge it.


The “heat-sink-impeller” (the finned, rotating component) consists of a disc-shaped heat spreader populated with fins on its top surface, and functions like a hybrid of a conventional finned metal heat sink and an impeller. Air is drawn in the downward direction into the central region having no fins, and expelled in the radial direction through the dense array of fins. A high efficiency brushless motor mounted directly to the base plate is used to impart rotation (several thousand rpm) to the heat-sink-impeller structure. The bottom surface of this rotating disc-shaped heat spreader is flat, such that it can mate with the top surface of the heat spreader plate described above.

During operation, these two flat surfaces are a separated by a thin (~0.03 mm) air gap, much like the bottom surface of an air hockey puck and the top surface of an air hockey table. This air gap is a hydrodynamic gas bearing, analogous to those used to support the read/write head of computer disk drive (but with many orders of magnitude looser mechanical tolerances).

Heat flows from the stationary aluminum base plate to the rotating heat-sink-impeller through this 0.03-mm-thick circular disk of air. As shown later in Figure 18, this air-filled thermal interface has very low thermal resistance and is in no way a limiting factor to device performance; its cross sectional area is large relative to its thickness, and because the air that occupies the gap region is violently sheared between the lower surface (stationary) and the upper surface (rotating at several thousand rpm). The convective mixing provided by this shearing effect provides a several-fold increase in thermal conductivity of the air in the gap region.

One important point about the air bearing is that the ~0.03 mm air gap is not maintained by using extremely tight mechanical tolerances. Much like an air hockey puck on an air hockey table, or a hard disk read/write head, the air gap distance is self-regulating. If the air gap distance increases, the air pressure in the gap region drops, which causes the air gap distance to decrease. This built in negative feedback provides excellent mechanical stability and an extremely stiff effective spring constant (important for ruggedness). Unlike an air hockey table, which relies on gravity to counter-balance the pressure force acting on the puck, the air-bearing cooler can be mounted in an arbitrary orientation (e.g., up-side-down, sideways, etc.). And unlike a computer disk drive, incidental mechanical contact between the two air bearing surfaces does not damage either surface.

[Twigsoffury]

My fractal cooler would kick its a@#

[NightrainSrt4]

A several fold increase in the thermal conductivity of the air in the gap still wouldn't put it in the league of aluminum or copper. Copper has ~16K times the thermal conductivity of air. A several fold increase on the air isn't even going to approach the effectiveness of copper. I don't know. Maybe I'm just not getting what they are trying to convey there.

[xr4man]

must have real world data on a cpu overclocked to convince me that the added complexity is worth it.

[SXRguyinMA]

My fractal cooler would kick its a@#

how about you replace their fin assembly with your fractal cooler for a spinning fractal cooler :D :whistler:

[mDust]

A several fold increase in the thermal conductivity of the air in the gap still wouldn't put it in the league of aluminum or copper. Copper has ~16K times the thermal conductivity of air. A several fold increase on the air isn't even going to approach the effectiveness of copper. I don't know. Maybe I'm just not getting what they are trying to convey there.

This.
I also do not think a .03mm air gap could conduct enough heat to effectively cool a CPU. That's about the size we fill with TIM...which is absolutely necessary. I'll believe it when I see it.
The tolerances elsewhere will have to be just as tight, which translates directly to cost...cost that will be passed up the chain to the consumer.


A high efficiency brushless motor mounted directly to the base plate is used to impart rotation (several thousand rpm)
I thought it was supposed to be more efficient? At several thousand RPMs it's going to loud and pretty dangerous...I'm talking cutting-stray-cables and missing-finger-tips-dangerous. I've been cut by case fans a few times, but there have only been a handful that I've had second thoughts about handling while spinning.

This air gap is a hydrodynamic gas bearing...
No, it's an aerodynamic gas bearing. Hydrodynamics is the study of liquid flow. Aerodynamics is the study of gas flow. Air is a fluid, but not a liquid. I don't like this article.

Heat flows from the stationary aluminum base plate
If this was designed to be so efficient, why is the base aluminum and not copper? I know copper costs ~4x as much, but it's ~63% more efficient at moving the heat to the fins...that's a pretty good gain right there.

The convective mixing provided by this shearing effect provides a several-fold increase in thermal conductivity of the air in the gap region.
Whoopty doo...from 0.024 W/(m.K) to .072 W/(m.K). Copper is 401 W/(m.K)...over 5500x more conductive than that air gap.

[crenn]

I also do not think a .03mm air gap could conduct enough heat to effectively cool a CPU. That's about the size we fill with TIM...which is absolutely necessary. I'll believe it when I see it.
The tolerances elsewhere will have to be just as tight, which translates directly to cost...cost that will be passed up the chain to the consumer.
Get a heated element, heat it up to 150c. Have your hand over a metre away, can you feel the heat? Move it closer, can you feel the heat now? etc etc until you have your hand nearly on the plate but not touching it, you can feel that heat now? The more you close the gap, the more you feel that heat (poor thermal conductivity), whether this is enough to translate the heat from the base plate to the impeller is another matter?
You do know that everything has tolerances, and in this case, I don't think the tolerances are that low because of how it's designed.


I thought it was supposed to be more efficient? At several thousand RPMs it's going to loud and pretty dangerous...I'm talking cutting-stray-cables and missing-finger-tips-dangerous. I've been cut by case fans a few times, but there have only been a handful that I've had second thoughts about handling while spinning.
It has a plastic guard on the top of the spinning impeller, you didn't read the paper.


No, it's an aerodynamic gas bearing. Hydrodynamics is the study of liquid flow. Aerodynamics is the study of gas flow. Air is a fluid, but not a liquid. I don't like this article.
Liquids are also fluids. Aerodynamic equations most likely have assumptions about the properties of air into them, hydrodynamics might have a few assumptions as well, but still have close enough to fluid dynamics. But fluiddynamic bearing doesn't sound that catchy, got to remember, some white papers are also marketing pitches as well. And when people think of Aerodynamics, they think of airplanes and fighter jets.


If this was designed to be so efficient, why is the base aluminum and not copper? I know copper costs ~4x as much, but it's ~63% more efficient at moving the heat to the fins...that's a pretty good gain right there.
Because the more you increase thermal conductivity, the harder it is to pull the heat away from the substance. But in this case, I agree with you that copper is probably a good move for this design, but aluminium is also a lot cheaper as far as I know, and in applications of cost effective designs, less material of a cheaper material, is better. Also copper weighs more.



Whoopty doo...from 0.024 W/(m.K) to .072 W/(m.K). Copper is 401 W/(m.K)...over 5500x more conductive than that air gap.
See the first part of this reply. Increasing the thermal conductivity is still an increase.

[mDust]

Get a heated element, heat it up to 150c. Have your hand over a metre away, can you feel the heat? Move it closer, can you feel the heat now? etc etc until you have your hand nearly on the plate but not touching it, you can feel that heat now? The more you close the gap, the more you feel that heat (poor thermal conductivity), whether this is enough to translate the heat from the base plate to the impeller is another matter?
I was going to say that your CPU would never get up to 150C, but with this cooler, I just don't know...:)
There is a difference between conduction and IR radiation. Your stovetop operates by conduction, your oven by convection, and the broiler in the oven by radiation. Light a match 2 inches under your hand. Does the 1300F (700C) flame burn a hole right into your hand? No, because air is nearly the worst conductor of heat...and conduction is what we're primarily concerned with here.


You do know that everything has tolerances, and in this case, I don't think the tolerances are that low because of how it's designed.
Yes, and 0.00118" is pretty tight regardless of how it is designed.


It has a plastic guard on the top of the spinning impeller, you didn't read the paper.
I did read the paper, however, I did not see any mention of a plastic cap or evidence of one in any of the pictures. My bad.


Liquids are also fluids. Aerodynamic equations most likely have assumptions about the properties of air into them, hydrodynamics might have a few assumptions as well, but still have close enough to fluid dynamics. But fluiddynamic bearing doesn't sound that catchy, got to remember, some white papers are also marketing pitches as well. And when people think of Aerodynamics, they think of airplanes and fighter jets.

Gas = Fluid
Liquid = Fluid
Gas ≠ Liquid
I'd sooner risk having to enlighten some people rather than sound like I have no idea what I'm talking about to those that I'm looking to impress. Since the disk is floating on a pocket of air, I would think that an airplane would be an appropriate analogy.

[RogueOpportunist]

CPU Cooling, heatsinks and "thermalwhatevveryouwannacallit" aren't new... There are certain things that have been "discovered" over the years, these things have been the primary reason the enthusiast cooling options are MUCH different than your standard consumer-grade cooling options... My "issue" with this little gadget is it isn't really introducing anything new or revolutionary, it is merely changing from a fan to an impeller... That's all it is.

I'm not saying this thing flat out won't work, I just have serious doubts about their claims... The idea being presented is basically that by converting to an impeller we can completely throw everything we know about heat pipes, heatsinks and metal out the window.

I judge based on what I know, not what I think I know... and I know I can't run my 4.3ghz core2 on passive cooling, I need airflow... I also know I can't run it on a stock heatsink, even if I reversed the flow of my shopvac and put a hundred+ CFM blowing directly on the heatsink, there just isn't enough metal for the heatsink/air relationship to function properly with the temperatures it needs to deal with... That is what I know from what I have tried in my own experiments, do I know the exact scientific information about heat exchange that I would need to to write a paper on the subject? No... I've just tried it, seen it not work and moved on... Now I'm looking at a potential product that has minimal amounts of metal, minimal airflow and a layer of air between the CPU and heatsink and I'm expected to take them at their word that this thing is going to cool better than current offerings on the market? I just don't know about that one.

It's this notion that moving metal through air is somehow going to solve some "problem" we have with moving air through metal that stinks like snake oil.