# Copper vs. Aluminum - Thermal Conductivity & Radiation



## DanishDevil (Jan 28, 2009)

First of all, I want to lay some ground rules, because I have seen this go way out of bounds on many other forums.

If you're going to make a claim, please voice your opinion and state WHY.

The question we are focusing on related to processor cooling, specifically with air cooling, not water cooling.  We can start a discussion for water cooling as well, but keep them separate and your comments specified and whether or not it makes a difference.

In a CPU heatsink, what is the best combination of copper and aluminum to extract heat away from the processor effectively, without having cost be a factor?

A few claims:



> Copper has a higher thermal conductivity, and therefore is superior to aluminum in processor cooling.





> Copper is better at conducting heat than aluminum, but aluminum is able to radiate the heat into the air better than copper because of its lower density.



Links to other topics discussing the issue:

http://episteme.arstechnica.com/6/ubb.x?q=Y&a=tpc&s=50009562&f=77909585&m=8490955581


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## Deleted member 24505 (Jan 28, 2009)

Does this mean copper coolers will work better with higher flow fans,and aluminium lower power fans?-



> Copper is better at conducting heat than aluminum, but aluminum is able to radiate the heat into the air better than copper because of its lower density.


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## ex-dohctor (Jan 28, 2009)

What about lapping of copper coolers? 

I've always lapped my CPU/GPU coolers as a habit. 

Mostly been using Thermal takes heatsink compound aswell. 

Seems to work a charm for me.


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## DanishDevil (Jan 28, 2009)

Not sure what this means about fan power.  The whole thermodynamics of cooling a processor has a lot of factors built into it.

As far as lapping, that doesn't really play into this discussion...


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## ex-dohctor (Jan 28, 2009)

Indeed, 

I must say that I started playing with Alu heatsinks in the beginning, but I have a marked preference for copper heatsinks with high speed/high volume fans attached to them. 

Even the passive heatsinks I fit to my customers RAM and G-card RAM is copper if I can find them. A mixture of Thermaltake and Coolermaster products. 

I just find that in my experience copper offers better cooling. 

Here in South Africa it isn't unusual for the daily ambient temps to reach 35'C - 40'C. 

So when you're running a high end machine and then OC'ing it, Copper Heatsinks suddenly become very important pieces of kit.


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## PVTCaboose1337 (Jan 28, 2009)

http://en.wikipedia.org/wiki/List_of_thermal_conductivities

Read it.  Copper is not much better than aluminum.


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## Thrackan (Jan 28, 2009)

Interesting stuff:
Here and here


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## Thrackan (Jan 28, 2009)

PVTCaboose1337 said:


> http://en.wikipedia.org/wiki/List_of_thermal_conductivities
> 
> Read it.  Copper is not much better than aluminum.



220 vs 350 (roughly) is quite the difference imho... over 50%


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## hat (Jan 28, 2009)

The best practical coolers have a copper base, usually heatpipes, and aluminum fins. Copper is better at heat transfer and aluminum is better at heat dissipation, so good heatsinks have a copper base that quickly/efficeintly gets the heat away from whatever is being cooled, heatpipes that quickly take the heat away from the base, and the heatpipes are attatched to aluminum fins that quickly dissipate heat. Some coolers are just a block with a copper base and aluminum fins. The aluminum absorbs heat away from the base and dissipates it at the fins. The heatpipe coolers are better though.

If coolers were just blocks temps would be much higher metal sandwiches with holes for tubing, they generally have some kind of pins inside the sandwich that gives much greater surface area for the water to make contact with the metal and dissipate the heat that way.

Silver is the best practical heat conductor, but it's too expensive to use in the place of copper. That's why we have arctic silver thermal paste. It's not a whole chunk of silver that's been put through metalworking processes, it's just silver dust mixed with some kind of thermal paste. Gold would be better but it's too expensive so it's not made. Diamond is the best, but they don't make that either, however I have seen a thread here on tpu about mixing diamond dust with other thermal paste for the absolute best stuff that can be made but I don't know where to start looking to dig that one up.


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## Thrackan (Jan 28, 2009)

hat said:


> The best practical coolers have a copper base, usually heatpipes, and aluminum fins. Copper is better at heat transfer and aluminum is better at heat dissipation, so good heatsinks have a copper base that quickly/efficeintly gets the heat away from whatever is being cooled, heatpipes that quickly take the heat away from the base, and the heatpipes are attatched to aluminum fins that quickly dissipate heat. Some coolers are just a block with a copper base and aluminum fins. The aluminum absorbs heat away from the base and dissipates it at the fins. The heatpipe coolers are better though.
> 
> If coolers were just blocks temps would be much higher metal sandwiches with holes for tubing, they generally have some kind of pins inside the sandwich that gives much greater surface area for the water to make contact with the metal and dissipate the heat that way.





> Myths About Materials/Coolants
> 
> Myth: Aluminum absorbs/dissipates heat faster than copper.
> 
> Reality: All thermal properties of copper are better than aluminum. Aluminum's advantage is that it is lighter and easier to machine. So, if one were given a pound of copper and a pound of aluminum, you might make a better performing heatsink with aluminum, as it might have more surface area to dissipate heat than copper for a given weight. Considering footprint limitations for air cooled CPU heatsinks, however, copper is definitely favored.



Shortly said, copper dissipates and conducts heat *better* at all times. Aluminum is just cost- and weightsaving (especially weight). See the first link in my previous post.


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## eidairaman1 (Jan 28, 2009)

good compromise cooler is copper plate with copper pipes going to aluminum fins,

cheapest solution is all aluminum

highest performing solution is copper (more dense material is the quicker stuff is conducted)

http://en.wikipedia.org/wiki/Heat_sink


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## OnBoard (Jan 28, 2009)

Copper, because it can store more heat -> gets hotter -> is higher above ambient (than aluminium) -> thus radiates heat better.

Or something like that I read that finally made sense to me on the matter.


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## ex-dohctor (Jan 28, 2009)

So what about the copper HS with the high volume/speed fan attached. 

Would that be the ideal combination?


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## Thrackan (Jan 28, 2009)

The best cooler would be:
High thermal conductivity
High surface area
Lots of coolant (air, water, whatever) touching the surface area.


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## DarkMatter (Jan 28, 2009)

As many have said copper is better. Full copper is better for cooling, but less practical (price, WEIGHT). A mixture of copper/aluminium can work as well as full copper in most practical situations though, because the cooler acts as a "capacitor" retaining the heat far from the CPU and dissipating it "slowly" (in comparison to full copper) doesn't matter too much. It also has the advantage of price and weight, specially weight, so with Al you can make more and bigger fins increasing surface area, mitigating the diference between Cu and Al.


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## DrPepper (Jan 28, 2009)

http://www.xbitlabs.com/articles/coolers/display/thermalright-true-copper-u120x_8.html#sect0

Note that the all copper design is not that much better but it is better than the aluminium one.


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## Thrackan (Jan 28, 2009)

DrPepper said:


> http://www.xbitlabs.com/articles/coolers/display/thermalright-true-copper-u120x_8.html#sect0
> 
> Note that the all copper design is not that much better but it is better than the aluminium one.



Thing is, it all comes down to about a square inch of contact between proc and cooler, and theres a max amount of heat that can be pulled away from that contact area.

Even the best cooler can only pull heat from that square inch and spread it throughout the cooler, which means that the "TRUE pure copper" is probably very near the maximum capacity you can pull away there.

The only thing that can increase your cooling capacity then is increase the difference in temp between CPU and ambient. Say with liquid nitrogen


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## ZenZimZaliben (Jan 28, 2009)

Actually the current technology is hitting it dead on. Use copper and copper heat pipes to remove the heat from the cpu, then use Al to dissipate that heat into the air, not only that but you have to consider the weight of the cooler. If some of these massive heatsinks we see today were made entirely out of copper it would weight like 3 lbs and would be way to much stress on the motherboard and socket. Especially for tower mounted motherboards, everyone would have to have desktop cases so the heatsink was directly down on the socket.

The best is a combo of Copper Core/Heat Pipes channeling that heat to Al Fins. AL is lighter and dissipates heat faster into the air. 

So in short. Copper is able to soak up heat faster due to its mass, but also because it has more mass it takes longer to cool down.


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## mrw1986 (Jan 28, 2009)

The best cooler is running your chip in mineral oil.


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## kysg (Jan 28, 2009)

hat said:


> The best practical coolers have a copper base, usually heatpipes, and aluminum fins. Copper is better at heat transfer and aluminum is better at heat dissipation, so good heatsinks have a copper base that quickly/efficeintly gets the heat away from whatever is being cooled, heatpipes that quickly take the heat away from the base, and the heatpipes are attatched to aluminum fins that quickly dissipate heat. Some coolers are just a block with a copper base and aluminum fins. The aluminum absorbs heat away from the base and dissipates it at the fins. The heatpipe coolers are better though.
> 
> If coolers were just blocks temps would be much higher metal sandwiches with holes for tubing, they generally have some kind of pins inside the sandwich that gives much greater surface area for the water to make contact with the metal and dissipate the heat that way.
> 
> Silver is the best practical heat conductor, but it's too expensive to use in the place of copper. That's why we have arctic silver thermal paste. It's not a whole chunk of silver that's been put through metalworking processes, it's just silver dust mixed with some kind of thermal paste. Gold would be better but it's too expensive so it's not made. Diamond is the best, but they don't make that either, however I have seen a thread here on tpu about mixing diamond dust with other thermal paste for the absolute best stuff that can be made but I don't know where to start looking to dig that one up.



think this is what you were talking about.

http://www.heatsinkfactory.com/ic-diamond-7-carat-thermal-compound-15-gram-p-16605.html


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## lemonadesoda (Jan 28, 2009)

> Copper is better at conducting heat than aluminum, but aluminum is able to radiate the heat into the air better than copper because of its lower density.


Now that, my friend, is bullsharks.  It is ONLY TRUE if your comparison is the same WEIGHT of fin... 100g of aluminium has more surface area than 100g of copper, assuming same "thinness" of the fin. But suggesting that lower density itself is the reason for higher cooling rates is so wrong the author of that statement is due a Darwin award.


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## 95Viper (Jan 28, 2009)

copper is the king, unless  ur on a budget, just my two cents.

http://www.thermshield.com/ThermshieldPages/Copper_vs_Aluminum.pdf

Check these guys(girls) out, catalog has a lot of info:http://www.thermshield.com/ThermshieldPages/Thermshield%20Catalog%20low-res.pdf
Their main page:http://www.thermshield.com/


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## Thrackan (Jan 28, 2009)

lemonadesoda said:


> Now that, my friend, is bullsharks.  It is ONLY TRUE if your comparison is the same WEIGHT of fin... 100g of aluminium has more surface area than 100g of copper, assuming same "thinness" of the fin. But suggesting that lower density itself is the reason for higher cooling rates is so wrong the author of that statement is due a Darwin award.



Exactly. If the *same volume and shape* is made out of both materials, copper will win hands down.

Furthermore, lower density would mean there's a relative lot of air in the aluminum, which would actually make it perform worse, like air pockets under your cooler base instead of TIM.


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## ZenZimZaliben (Jan 28, 2009)

Diamond (2300 W/mK) 
Pyrolytic Graphite (1950 W/mK) 
Silver (429 W/mK), 
Pure Copper (401 W/mK), and 
Pure Aluminum (237 W/mK)

The physical action of conduction/convection relies solely on the two material's individual thermal conductivities, their proximity to each other, and their time in contact with each other. Thus, a pure copper heatsink will always outperform a heatsink of the exact same geometry of a pure aluminum heatsink assuming that both have the same contact with the heat source and the same rate of airflow over the surface.

That is as basic as it gets...

The difficult problem is we are restricted. The heatsink can only have so much mass before it hurts the motherboard or cracks the IHS or just goes beyond load specs. We are also limited to the physical size of the heatsink. This is why we are seeing all these really cool heatpipes and copper/AL mixed blocks. So you have to run hybrid heatsinks to get the largest surface area in a small space and the most mass it can have without going over specs.


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## suraswami (Jan 28, 2009)

DanishDevil said:


> First of all, I want to lay some ground rules, because I have seen this go way out of bounds on many other forums.
> 
> If you're going to make a claim, please voice your opinion and state WHY.
> 
> ...




All I know is Cooking with a copper vessel tastes far better than aluminum vessel


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## FordGT90Concept (Jan 28, 2009)

ZenZimZaliben said:


> The difficult problem is we are restricted. The heatsink can only have so much mass before it hurts the motherboard or cracks the IHS or just goes beyond load specs. We are also limited to the physical size of the heatsink. This is why we are seeing all these really cool heatpipes and copper/AL mixed blocks. So you have to run hybrid heatsinks to get the largest surface area in a small space and the most mass it can have without going over specs.


QFT: it's all about mass.


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## eidairaman1 (Jan 29, 2009)

suraswami said:


> All I know is Cooking with a copper vessel tastes far better than aluminum vessel



http://en.wikipedia.org/wiki/Copper_toxicity

read that and you may want to think twice.


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## P4-630 (Jan 29, 2009)

A copper heatsink with fan runs warmer and it takes a longer time to cool down unlike an aluminium heatsink that cools down fast with fan, also lots of copper warms up your case more then aluminium heatsinks. But yet copper does a better good job in getting the heat away from processor cores.


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## suraswami (Jan 29, 2009)

eidairaman1 said:


> http://en.wikipedia.org/wiki/Copper_toxicity
> 
> read that and you may want to think twice.



To me Wikipedia = bunch of jobless idiots blaberring something and some nut hosts that.

You know best cooking is with mud pot


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## kiriakost (Jan 29, 2009)

The first successful  CPU cooler design  was the SLK-900 heatsink  . 

Never ever before, any heatsink had a similar  shape . 

The special thin fins design , offered the air flow that the copper needs,
so to transfer the heat away. 

The SLK-900 heatsink block size cooler , is our successful past . 

The heat pipes , are one failure as design in my eyes , it offers more choices at building coolers industry, 
so to be creative and make several designs , but the bottom line are,
that is less effective, than block design heatsink s.

All latest high performance  copper (coolers - heatsink s) ,  using the same thin fins design, 
that we have see at the  SLK-900  , before five or six years back. 

This design is the end of the road about high air flow on copper . 

ALPHA  famous heatsinks  designer from Japan, did first worldwide , the copper base with aluminum fins.

If we need to learn and understand , we have to examine the past.  



.


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## aspire (Jan 29, 2009)

P4-630 said:


> A copper heatsink with fan runs warmer and it takes a longer time to cool down unlike an aluminium heatsink that cools down fast with fan, also lots of copper warms up your case more then aluminium heatsinks. But yet copper does a better good job in getting the heat away from processor cores.



The reason copper takes a long time to cool down is due to it's higher specific heat. Quite simply it holds more energy than aluminum does.

Therefore aluminum is not better for dissipating heat, it's just able to dump its lower amount of energy faster, which should not be a big surprise...


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## DanishDevil (Jan 29, 2009)

So if copper has a higher specific heat than aluminum, if they were both loaded with the same amount of heat (same temperature) which would radiate its heat into the air with the aid of a fan faster?  I see a contradiction in your post.


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## aspire (Jan 29, 2009)

DanishDevil said:


> So if copper has a higher specific heat than aluminum, if they were both loaded with the same amount of heat (same temperature) which would radiate its heat into the air with the aid of a fan faster?  I see a contradiction in your post.



There is a glaring contradiction in your post. Having the same amount of heat does not mean the two metals are at the same temperature.

For example lets say you take 2 metal cubes each 1kg, one copper and one aluminum.

You then transfer 100 joules of heat/energy into each. The copper block will be cooler than the Aluminum one because of it's higher specific heat, essentially it takes more heat to raise 1 gram of copper one degree Celsius than to do the same with aluminum.

L2Physics everyone... :shadedshu


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## Laurijan (Jan 29, 2009)

Quote:
Copper has a higher thermal conductivity, and therefore is superior to aluminum in processor cooling.  

Quote:
Copper is better at conducting heat than aluminum, but aluminum is able to radiate the heat into the air better than copper because of its lower density.  

+1


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## Thrackan (Jan 29, 2009)

Laurijan said:


> Quote:
> Copper has a higher thermal conductivity, and therefore is superior to aluminum in processor cooling.
> 
> Quote:
> ...



Seriously, what's with the lower density thing? Aluminum has a *higher thermal resistance*, which results in it being *harder to change temperature in the material*, regardless of whether you *cool* or *heat* it.


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## lemonadesoda (Jan 29, 2009)

:shadedshu

I find this thread very sad and disappointing. I thought TPU members had a little more scientific knowledge and understanding.

What is also very sad is that due to the w1zzards superb google placings, this thread now comes to the top of a search. How terrible for someone who *really wants to understand.* So many posts in this thread spout or "+1" total bullsharks.

http://en.wikipedia.org/wiki/Heat_sink
http://www.heatsink-guide.com/
... AND your skool physiks book.


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## DanishDevil (Jan 29, 2009)

aspire said:


> There is a glaring contradiction in your post. Having the same amount of heat does not mean the two metals are at the same temperature.
> 
> For example lets say you take 2 metal cubes each 1kg, one copper and one aluminum.
> 
> ...



Sorry that I'm not a physics major...sheesh.  I created this thread to learn the truth...

-----------------------------------------------------------

Clearly, different people have different opinions here.  What I would like to do is organize a sort of forum debate.  We need a good couple of scholarly sources (most likely physics-related materials) and figure out what really is best for heatsinks.


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## Thrackan (Jan 29, 2009)

DanishDevil said:


> Sorry that I'm not a physics major...sheesh.  I created this thread to learn the truth...
> 
> -----------------------------------------------------------
> 
> Clearly, different people have different opinions here.  What I would like to do is organize a sort of forum debate.  We need a good couple of scholarly sources (most likely physics-related materials) and figure out what really is best for heatsinks.



Apparently, a lot of those opinions are backed by no facts at all. I advise you to look into the following terms yourself to get a well-based opinion:
- Thermal Resistance
- Thermal Conductivity

Both these terms already take into account the density of the material.
Also, keep in mind that copper has a higher mass per volume (1 cubic foot of copper weighs more than 1 cubic foot of aluminum) and be aware which of these terms apply to *volume* and which apply to *mass*.

Might be a little scientific journey, but since everyone rolls over each other with opinions here, creating chaos and confusion, the best way to find out is investigate it yourself using cold, hard facts.

At this moment in time you probably still don't know which opinion on this thread is correct and which ones are based on urban legends and common misconceptions. Unfortunately, that's exactly what you get when asking about something which has common misconceptions in the general public.


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## DanishDevil (Jan 29, 2009)

That's why I want somebody to quote a *scholarly source* that everybody can trust, and answer the question in order to kill the myths once and for all, because there *are* too many web sites and forums that have opinions that are incorrect.


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## Thrackan (Jan 29, 2009)

Best thing is that people don't even trust facts on Wikipedia anymore lately... Which makes it kind of hard to quote a good source here.
I could quote the numbers out of my physics book, but numbers alone don't say much do they?


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## DanishDevil (Jan 29, 2009)

Then maybe somebody else can find something...that's why I made this public.

Wikipedia will not be good enough, as it can be user-edited.

This would be a sick Physics class project to explain and justify why one is better than the other


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## kiriakost (Jan 29, 2009)

DanishDevil said:


> This would be a sick Physics class project to explain and justify why one is better than the other



Not really ,  because far from numbers and need for knowledge , you have left out side the machinist who will create for you,  one working heatsink. 

One cube of material is unable to offer anything . 

So ,  more important than metal , are the design . 
After the successful design comes the metal . 
And the limitations of handling the metal . 

Aluminum are soft !!   There is no way to make one thin fins design with aluminum body. 

Lets  talk about things that are possible to be created , and *not imaginary* .

*Technology of 1997  1998 ...*  ALPHA P3 125
http://two.xthost.info/kiriakost/html/1998.html


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## DanishDevil (Jan 29, 2009)

We're not talking about design.  We are talking about the popular coolers of today, like the Zalmans and the Xigmateks.  

*The question now is, aluminum or copper fins, regardless of weight or price.  Which offers better performance?*


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## kiriakost (Jan 29, 2009)

And if you do not know how to evaluate coolers by their design  , how in earth you could possible tell,
which one are the best , you will buy them all ?


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## Thrackan (Jan 29, 2009)

First off, don't mistake theory for imagination.
Second, about popular coolers on the market today, each cooler which has both a pure copper and mixed or alu version proves that the pure copper version does better.


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## P4-630 (Jan 29, 2009)

kiriakost said:


> Aluminum are soft !!   There is no way to make one thin fins design with aluminum body.



I do not 100% agree with that.
Yes aluminium is soft for machining but there are many grades of aluminium available...

Many designs can be realized, but "perfect(or better)" heatsinks may become very expensive depending on the design, material and fabrication process.


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## kiriakost (Jan 29, 2009)

P4-630 said:


> I do not 100% agree with that.
> Yes aluminium is soft for machining but there are many grades of aluminium available...



Oh if we head that way " grades of aluminum " , we lost in the "heat transferability game "  .


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## Thrackan (Jan 29, 2009)

P4-630 said:


> I do not 100% agree with that.
> Yes aluminium is soft for machining but there are many grades of aluminium available...
> 
> Many designs can be realized, but "perfect(or better)" heatsinks may become very expensive depending on the design, material and fabrication process.



I agree on the grades, I've seen specifications for top- and low grade aluminum at work and it's a world of difference.


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## Thrackan (Jan 29, 2009)

kiriakost said:


> Oh if we head that way " grades of aluminum " , we lost in the "heat transferability game "  .



Copper has grades of quality too..


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## kiriakost (Jan 29, 2009)

Thrackan said:


> Copper has grades of quality too..



I do not argue on that ,  but no one from the big names on heatsinks , 
will use cheap stuff .

The performance loss would be tragic, and the fame of the product doomed.


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## Thrackan (Jan 29, 2009)

Well, I just checked a spec report here:
High-grade aluminum is 99.8+ % Al and the rest is mostly Fe, Cd, Hg and Pb
Low-grade aluminum is ~99.2% Al with the same "rest" elements.

For construction work and car wheels etc, that makes a dumpload of difference, but for a heatsink that's near nothing.


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## Deleted member 3 (Jan 29, 2009)

ZenZimZaliben said:


> not only that but you have to consider the weight of the cooler.



From a cooling standpoint it doesn't really matter. Besides, socket 604 (Nocona) and 771 have bolts going through the motherboard right into the case, which effectively makes it irrelevant that you have 2KG of coolers hanging in your case. The stock heatsinks are pure copper. 


Apart from that, seeing Farnsworth next to text makes me believe the text easier.


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## 95Viper (Jan 29, 2009)

lemonadesoda said:


> :shadedshu
> 
> I find this thread very sad and disappointing. I thought TPU members had a little more scientific knowledge and understanding.
> 
> ...



Free advertising! 



DanishDevil said:


> That's why I want somebody to quote a *scholarly source* that everybody can trust, and answer the question in order to kill the myths once and for all, because there *are* too many web sites and forums that have opinions that are incorrect.





DanishDevil said:


> Then maybe somebody else can find something...that's why I made this public.
> 
> Wikipedia will not be good enough, as it can be user-edited.
> 
> This would be a sick Physics class project to explain and justify why one is better than the other





kiriakost said:


> Not really ,  because far from numbers and need for knowledge , you have left out side the machinist who will create for you,  one working heatsink.
> 
> One cube of material is unable to offer anything .
> 
> ...





kiriakost said:


> And if you do not know how to evaluate coolers by their design  , how in earth you could possible tell,
> which one are the best , you will buy them all ?





95Viper said:


> copper is the king, unless  ur on a budget, just my two cents.
> 
> http://www.thermshield.com/ThermshieldPages/Copper_vs_Aluminum.pdf
> 
> ...



If you looked here,at the links in my post, you would have got your info. I think they know how to design, evaluate, and build them.  I believe that engineer has studied the facts.

It seems to be a case of I (not refering to me personally, read next sentence)am right you and the rest of the world is wrong.  Facts are facts.

I don't know because I never studied thermal properties in school.  So, I go by what scholars, eng., research labs and such, come up with and publish.  READ.

Have a good day.


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## Odin Eidolon (Jan 29, 2009)

copper is much better. the physics regarding this is pretty simple IMHO.

however, making a simple example, TRUE copper> TRUE aluminium by a fair margin, and with every fan speed. since the only difference (apart from weight ofc) between those two coolers is the material, we can deduce that copper is better.


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## ZenZimZaliben (Jan 29, 2009)

DanTheBanjoman said:


> From a cooling standpoint it doesn't really matter. Besides, socket 604 (Nocona) and 771 have bolts going through the motherboard right into the case, which effectively makes it irrelevant that you have 2KG of coolers hanging in your case. The stock heatsinks are pure copper.
> 
> 
> Apart from that, seeing Farnsworth next to text makes me believe the text easier.



Good News Everyone!!

I dont agree with you though. You have never had a video card or motherboard that was warped from all the weight? Even with rods going through the motherboard the PCB can flex and after a long enough time it will warp. This really only happens on video cards and tower mounted motherboards, where the entire weight of the cooler is hanging off the socket.


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## Odin Eidolon (Jan 29, 2009)

ZenZimZaliben said:


> Good News Everyone!!
> 
> I dont agree with you though. You have never had a video card or motherboard that was warped from all the weight? Even with rods going through the motherboard the PCB can flex and after a long enough time it will warp. This really only happens on video cards and tower mounted motherboards, where the entire weight of the cooler is hanging off the socket.



he just said:


DanTheBanjoman said:


> bolts going through the motherboard right into the case



weight is not hanging off the socket like you said, but off the motherboard tray


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## ZenZimZaliben (Jan 29, 2009)

Oh..through the entire motherboard tray? Never seen that. Cool!


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## Deleted member 3 (Jan 29, 2009)

ZenZimZaliben said:


> Good News Everyone!!
> 
> I dont agree with you though. You have never had a video card or motherboard that was warped from all the weight? Even with rods going through the motherboard the PCB can flex and after a long enough time it will warp. This really only happens on video cards and tower mounted motherboards, where the entire weight of the cooler is hanging off the socket.



The bendering part is a mounting problem caused by weight, not cooling. And as I stated, on s604/771 the issue isn't really there since the coolers aren't mounted to any PCB.


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## DrPepper (Jan 29, 2009)

I still say its easy to comapre the true al versus the true cu and see which is better. This way it takes variables like design and thickness of fins etc out of the equation. I don't see how aluminium dissipates heat any faster than copper I thought that was dependant on what it was transferring the heat to which in both cases is air.


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## DarkMatter (Jan 29, 2009)

DrPepper said:


> I still say its easy to comapre the true al versus the true cu and see which is better. This way it takes variables like design and thickness of fins etc out of the equation. I don't see how aluminium dissipates heat any faster than copper I thought that was dependant on what it was transferring the heat to which in both cases is air.



I agree, nothing better than actual coolers to show the diffference. The Zalman VF-700 is another example, I have had both -Cu and -AlCu and it makes a world of a difference.

I don't know where the "Al dissipates better to air" thing comes, but it's not true. It must come from someone saying x grams of Al fins dissipates more heat than the same mass of Cu fins or something. In that case it's (probably*) true, because Al fins could have 3x the surface of comparable Cu fins, but that's all.

*Remains to be seen IMO. If both where given the same airflow the smaller Cu one could still dissipate better. The problem?? Cu would require a smaller, faster and noisier fan to achieve the same airflow.


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## shadow0000 (Feb 12, 2009)

I think copper is much better to use than the aluminum, cause copper is can absorb the heat and change a cool, but the aluminum i don't think so if they can absorb heat and change it to cool..



__________________
Copper Sinks


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## Odin Eidolon (Feb 12, 2009)

shadow0000 said:


> I think copper is much better to use than the aluminum, cause copper is can absorb the heat and change a cool, but the aluminum i don't think so if they can absorb heat and change it to cool..
> 
> 
> 
> ...



not really a scientific explanation uh?


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## kiriakost (Feb 12, 2009)

The basics of cooling electronic parts , are well know at the last 40 years , VCRs - TVs - Audio systems .... all gets sufficient cooling . 

What is under investigation are ,  high performance coolers at low price . 

If price was not an issue ,  Gold and Silver  are the top metals for the job


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## LAN_deRf_HA (Feb 12, 2009)

I don't get why this went past the first page. As stated repeatedly copper is best, but weighs and cost more, so that's why we see the copper pipe aluminum fins combo so often. What else needs to be said?


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## lemonadesoda (Feb 12, 2009)

Copper is so cheap (less than $5 per kg), it is amazing that any decent "aftermarket" cooler over $25 is made from anything BUT copper. It doesnt even have to be the highest grade copper. But there you go, that's the economics of distribution.

Take a $40 cooler. $5 tax. $10 to the retailer, and $5 to the distributor/wholesaler. $3 on international shipping. $3 on advertising. $3 on packaging. $3 on the fan and mounting system. What's left? $8. From that you need to design, manufacture and make a profit. So OK... it's amazing any cooler under $40 isnt made from plastic! LOL


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## DrPepper (Feb 12, 2009)

lemonadesoda said:


> Take a $40 cooler. $5 tax. $10 to the retailer, and $5 to the distributor/wholesaler. $3 on international shipping. $3 on advertising. $3 on packaging. $3 on the fan and mounting system. What's left? $8. From that you need to design, manufacture and make a profit. So OK... it's amazing any cooler under $40 isnt made from plastic! LOL


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## 3870x2 (Feb 12, 2009)

lemonadesoda said:


> Copper is so cheap (less than $5 per kg), it is amazing that any decent "aftermarket" cooler over $25 is made from anything BUT copper. It doesnt even have to be the highest grade copper. But there you go, that's the economics of distribution.
> 
> Take a $40 cooler. $5 tax. $10 to the retailer, and $5 to the distributor/wholesaler. $3 on international shipping. $3 on advertising. $3 on packaging. $3 on the fan and mounting system. What's left? $8. From that you need to design, manufacture and make a profit. So OK... it's amazing any cooler under $40 isnt made from plastic! LOL



as has already been stated, it is easier to remove the heat from aluminum, therefor a copper base and aluminum fins would be better than a whole copper setup.


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## aspire (Feb 12, 2009)

3870x2 said:


> as has already been stated, it is easier to remove the heat from aluminum, therefor a copper base and aluminum fins would be better than a whole copper setup.



Again, this is a stupid myth that has been perpetuated for far too long.


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## DrPepper (Feb 12, 2009)

3870x2 said:


> as has already been stated, it is easier to remove the heat from aluminum, therefor a copper base and aluminum fins would be better than a whole copper setup.



Don't copper and aluminium dissapate heat equally efficiently in air unless they have different insulating properties.


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## kiriakost (Feb 12, 2009)

aspire said:


> Again, this is a stupid myth that has been perpetuated for far too long.



No its not a myth ... but wait a minute ... are you metallurgist ? 

Calling stupid , something that you have no knowledge of it , its stupid by it self.


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## aspire (Feb 12, 2009)

kiriakost said:


> No its not a myth ... but wait a minute ... are you metallurgist ?
> 
> Calling stupid , something that you have no knowledge of it , its stupid by it self.



Care to try and find me information from any reputable source stating that aluminum dissipates heat faster than copper?


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## kiriakost (Feb 12, 2009)

DrPepper said:


> Don't copper and aluminium dissapate heat equally efficiently in air unless they have different insulating properties.



Its all about the interior  structure of the metal ... 

I am not specialist , but i work with metals , aluminum looks to have a crystallized composition.
The crystallized composition  makes it not that solid, but lightweight.  

Copper has more compressed structure , at the end,  two similar shaped & sized  items , will show the copper one as heavier .

Since copper has a more compressed structure  , electrons flow faster . 

Heat from the other hand, mimics the electrons flow , because " Heat = energy "

The Aluminums crystallized composition, helps heat to escape better , because radiates the heat better .   

Coppers compressed  " crystallized composition "  has more mass ,  so it radiates less . 

Metals with truly high composition "compressed structure"  like Steel,
offers mechanical strength, but they are even poorer as heat radiators . 

Its good that we have so many options as metals , its one offers special ability s ,
to chose and use .


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## 3870x2 (Feb 12, 2009)

figured it was common metallurgic knowledge that a metal that is less dense will release heat quicker.  Guess i was wrong?¿?¿

EDIT: what he said ^^
common sense guys, pay attention.


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## kiriakost (Feb 12, 2009)

aspire said:


> Care to try and find me information from any reputable source stating that aluminum dissipates heat faster than copper?



Try school books .


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## aspire (Feb 12, 2009)

While this might be the case in a large block of metal, the amount of heat that the thin fin of a heatsink of radiator makes the difference in time needed to dissipate the same amount of heat negligible.

On top of the fact that these fins never get hot to begin with. As I've said in other threads, if your heatsink (tower style) is ever hot to the touch, you have an airflow problem.

All in all, copper is the most practical metal to use in terms of performance cooling.



kiriakost said:


> Try school books .



So sorry, never had the opportunity to take a metallurgy class.


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## 3870x2 (Feb 12, 2009)

aspire said:


> While this might be the case in a large block of metal, the amount of heat that the thin fin of a heatsink of radiator makes the difference in time needed to dissipate the same amount of heat negligible.
> 
> On top of the fact that these fins never get hot to begin with. As I've said in other threads, if your heatsink (tower style) is ever hot to the touch, you have an airflow problem.
> 
> All in all, copper is the most practical metal to use in terms of performance cooling.



ok try this:
why do most heat sinks feature aluminum fins? even very high end HSFs?
this excludes zalman, they do it for looks.


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## kiriakost (Feb 12, 2009)

aspire said:


> So sorry, never had the opportunity to take a metallurgy class.



Now you speak reasonably ... take care .


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## technicks (Feb 12, 2009)

3870x2 said:


> ok try this:
> why do most heat sinks feature aluminum fans? even very high end HSFs?
> this excludes zalman, they do it for looks.



Ever thought of the price?


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## kiriakost (Feb 12, 2009)

3870x2 said:


> ok try this:
> why do most heat sinks feature aluminum fans? even very high end HSFs?
> this excludes zalman, they do it for looks.



aluminum fans BODY .... ?


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## 3870x2 (Feb 12, 2009)

kiriakost said:


> aluminum fans BODY .... ?



o snap! change fans -> fins.


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## DanishDevil (Feb 12, 2009)

Read the OP guys.  This is REGARDLESS of weight and price.  This is STRICTLY on cooling.

I personally haven't seen a truly well-organized explanation to convince everybody quite yet.  I'd love to see something like a scanned page from an up to date college physics textbook.


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## DrPepper (Feb 12, 2009)

kiriakost said:


> Its all about the interior  structure of the metal ...
> 
> I am not specialist , but i work with metals , aluminum looks to have a crystallized composition.
> The crystallized composition  makes it not that solid, but lightweight.
> ...



Then if that is true then why does the aluminium true perform worse than the copper one.


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## technicks (Feb 12, 2009)

> There are a few substances that are at the top of the thermal conductivity charts, namely:
> 
> Diamond (2300 W/mK)
> Pyrolytic Graphite (1950 W/mK)
> ...



Sums up pretty much how it think about it.


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## wahdangun (Feb 12, 2009)

maybe becouse aluminium fin can't absorb heat faster enough, to radiates the heat, so that's why pure copper HSF use higher, louder fan to compensate it so it will perform better meanwhile aluminium fin can't use that, bacouse it can't absorb heat faster,

it just like video card, if gpu isn't fast enough than it useless to use higher bandwidth take example hd 2900 xt and 3870, depsite hd 2900xt use 512 bit compare with 256 bit in 3870 they still perform same(same like almunium depsite it can radiates heat beter but it can't absorb heat fast enough) , and now take a look on hd 4850 and 4870 so why they perform difrent?, it's becouse hd 4870 use GDDR5 and the GPU is fast enough to use all the bandwidth(same with copper, becouse it can absorb heat fast enough, it will perform better if it use higher, louser fan)


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## FordGT90Concept (Feb 12, 2009)

Here is a paper authored by a Candian doctor that does scientific testing on all aluminium, all copper, copper base with aluminium fins, and alumninum base with copper fins tested using a 585W block heater in a wind tunnel.  Unforunately, it is not free to view it:
http://powerelectronics.com/thermal_management/heatsinks/power_tests_compare_forced/


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## kiriakost (Feb 12, 2009)

FordGT90Concept said:


> Here is a paper authored by a Candian doctor that does scientific testing on all aluminium, all copper, copper base with aluminium fins, and alumninum base with copper fins tested using a 585W block heater in a wind tunnel.  Unforunately, it is not free to view it:
> http://powerelectronics.com/thermal_management/heatsinks/power_tests_compare_forced/



Nice link , not that explanatory for the young reader . 

But the base idea  its not focused on the metals it self , but on archiving best results . 

what is a fact so far , are those :
1) Thermal energy  travel and spreed faster on copper . 

2) aluminum is not fast as copper , so its common on large heatsinks , even if they are large , the source of heat creates a hot spot , so the side fins does not share the same load.

3) The Mix of copper base ( better distribution of energy ) , plus aluminum fins , makes the all heatsink  100%  active  =  " effective " , and lightweight.

I believe that what counts more as  loss about thermal transfer, its the poor ability of aluminum , to spread the thermal load equally , on the back plate of the heatsink. 

The latest  INTEL heatsinks for the Prescott (socket 478 ) were round shaped aluminum ,
with a copper rob  , crossing it from top to bottom.  

INTEL start using on P4 CPUs .. Heat spreaders ... after lapin them , you can see the copper to shine.
They did that so to help aluminum heatsinks to be more effective .


.


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## Stefandi (Feb 25, 2014)

Can I conclude copper heatpipes are better than alumunium ones regardless the base? I had recently bought my graphic card, but never to see heatpipes made by silvery alumunium


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## eidairaman1 (Feb 25, 2014)

Some copper heatpipes are being dipped in zinc plating for show


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## Stefandi (Feb 27, 2014)

eidairaman1 said:


> Some copper heatpipes are being dipped in zinc plating for show



Can you confirm Leadtek WinFast GTX760 OC Dual Fan heatpipes are copper indeed dipped in Zinc? 
I've contacted the LeadTek and they said the liquid is pure water. As far as I know water only viable to Copper, Monel, Nickel, Titanium. See http://www.thermacore.com/thermal-basics/heat-pipe-technology.aspx for more info.


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## Arjai (Feb 27, 2014)

I am not all that experienced of a Welder but, Brazing Copper? HOT! It will burn you a minute later.

Aluminum? Tig welding is a lower temp process, but still plenty hot. Inside fifteen seconds, Al is mostly cool to the touch.

Copper, takes longer to heat. Aluminum is hot five feet from the weld, now!

I need to study my Metallurgy book, if I have any time, to see if there is a section specifically about thermal characteristics, hopefully a chart I can photograph.

My, current, two cents.


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## Arjai (Feb 27, 2014)

Arjai said:


> I am not all that experienced of a Welder but, Brazing Copper? HOT! It will burn you a minute later.
> 
> Aluminum? Tig welding is a lower temp process, but still plenty hot. Inside fifteen seconds, Al is mostly cool to the touch.
> 
> ...


Do have that backwards? I have been drinking.. I know Steel takes forever to cool, Copper is quick to cool as is Al. but copper, you can hold a corner in your hand, and weld the other corner, Aluminum will burn you doing that...As will steel. But Al will cool real fast!

OK, I think that is right!


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## Designer (Aug 31, 2017)

It's been 9 years since this thread was started and 3 years since the last post.  We designed and built data centers for 15 years or so and encountered the heat transfer problems talked about in this thread.
Our Findings:

Cooling CPU's is a basic heat transfer problem.  
All the rules of heat transfer and thermodynamics apply (go grab those college thermo textbooks).
Heat (BTU's) can only flow from a higher temperature source to a lower temperature sink (explained by the second law of thermo)
The rate of heat flow thru a substance (metal or air) is a direct relation of the temperature difference (delta T)  between the hot side and cold side. Heat transfer equations.
The Greater the delta T, the greater the heat transfer. 
The rate of heat flow (for a given delta T) is a reverse relation to the material's resistance to heat flow.  This is the R value.
Materials with high R values are "insulators".  Materials with low R values are "conductors.
The heat in our example starts at the circuit connection (transistors), and goes thru all the metals until it gets to the air circulating around the fins on the sink.
OBTW, the air circulating around the fins has to eventually be cooled (have its heat removed) and then be returned to the fins.
The overall heat transfered thru the system is a function of the thermal resistances of all materials added together.
This is very similar to the phenomena of adding the resistance values of electrical resistors that are wired in series to obtain an overal resistance value.
The metal discussion revolves around the thermal conductance values of the various metals.  Or in our case, the "resistance values".  The resistance values are a function of the materials thickness and its conductance values.
When examining materials in series, the total resistance value is highly affected by the material with the highest R value (much like electrical resistors). That value is the "weakest link" in the system.
The data (resistance values) of the materials involved show that copper is superior to alumunum.  
But also, the weakest link is the R value of air.  Air is a lousy heat transfer material.
This is where the research on liquid cooling for processors comes in to the discussuon.
Thanks for the Forum


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## rtwjunkie (Aug 31, 2017)

@Designer welcome to TPU!

That was a nice breakdown of all the factors involved.


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## Asuredawn (Sep 2, 2017)

Things sure have come a long way, thanks Designer!

I now see that copper diamond and diamond heatsinks are the future! 
(Please forgive the somewhat sarcastic but also slightly serious and hopeful statement above)


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## lilhasselhoffer (Sep 3, 2017)

Let's talk theory first.

In a cooler you're looking to transfer heat from point A to point B.  The heat transfer method is primarily conduction.  The other options just aren't reasonable (convection and radiation).  Conduction works mathematically as such:

q = k A dT / s   
q = heat transfer (W, J/s, Btu/hr)
A = heat transfer area (m2, ft2)
k = thermal conductivity of material (W/m K or W/m oC, Btu/(hr oF ft2/ft))
dT = temperature gradient - difference - in the material (K or oC, oF)
s = material thickness (m, ft)
http://www.engineeringtoolbox.com/conductive-heat-transfer-d_428.html  is the source, though if you crack open any book on thermodynamics it is there.

What does this tell us?
1) Larger values of A, K, and larger difference in temperature between two surfaces will raise how much heat can be transferred.
2) Smaller thickness to conduct through will increase heat transfer rates.


This means that the copper can conduct more heat.  If you had copper and aluminum in the same shape (not mass), then you'd be able to run a hotter CPU with copper, or a smaller delta T between the processor and environment (read: cooler CPU temperatures).


Let's take a look at something else new.  Nickel plating.  Why would you do this?  The secret here is also geometry.  If your increase in surface area (A) is greater than your decrease in q, then you're still going to transfer more energy.  If you have a thin enough coating, you could cover a copper heatsink in plastic and it would still transfer more heat.  



TL: DR
The best heat sink is copper, has a large surface area, and is designed to include the smallest possible distance between fins and CPU.

I know this is a double post, but the topic is huge.


Theory time over. Let's talk practical math.  Why are coolers designed the way they are?
1) Heat pipes exist to transfer heat over long distances, without having to heat up.
2) Larger surface area means more heat transfer.
3) Exotic materials are costly.
4) Cooler design is why you paid attention in college level mathematics, and why you pay an engineer with software to model it.


So let's look at a simple cooler, and make up some numbers.

CPU A puts out a maximum TDP of 65 watts.  You build two coolers, and test the aluminum one.  It registers a CPU temperature of 50 degrees above the ambient temperature of 20 C.  What is the temperature of the copper cooled CPU?

q = 65 = k*A*(T1-T2)/s
Separating out what we know, the values of A and s are constant because they are related to geometry.  q is a constant, based upon the TDP of the CPU.  This means the equations becomes:
65*s/A = k*(T1-T2).
For the aluminum, 65*s/A = 205*(70-20) therefore s/A = 157.6923
Plugging that into the equation,
65 *157.6923/401 = (T1-T2), therefore T2 = 45.56 degrees C



Now the doozy.  Heat transfer is going on constantly.  This is why if you look at a heat sink sideways in a FLIR camera the part closest to the source is lighter (thus hotter) than that away from the source.  Functionally this means that your heat transfer is lesser as your s value increases.  The only way to model this is using partial differential equations to iterate the heat transfer function.

If you understood the above, your nose should already be bleeding.  If you didn't, let's simplify this as "run a butt load of simulations which depend upon one another for a final solution."  This is why finite element analysis programs exist (besides modelling tensor mathematics to simulate loading scenarios).


*deep breath*

In practice, this is why we love heat pipes.  

Heat pipes use a phase change to make transferring energy very low loss, mathematically they minimize the "s" value in the conduction equation.  Put simply, the CPU dumps a bunch of energy to vaporize water, which floats to a cooler area, and condenses.  This is why heat pipes don't require specific orientations (if they have an internal wick to make sure they condense and flow back to the CPU contact surface).  As you control the location with the fins (because the vaporization energy of water is insanely high), the s value becomes very small. 




Now about a year ago there was a less than kind sharing of words.  I called someone out, because they couldn't express the above in units, and didn't understand why cooling worked differently with huge delta T values (as in an AC unit) than with low delta T values (as in water cooling).

I plundered the values for my example form here:
http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

Note that k values change based upon ambient temperature, and that water has a really low (0.58) value.  In practice this means, because water has both low conductivity and high specific heat values, it is fantastic at taking heat from point A to point B with very little loss simply because of a small delta temperature with the environment.  As you maintain the temperature of the water rather well, once you hit the heat sink the maximum amount of energy can be dumped.


Again,
TL: DR
Water cooling and heat pipes are means by which conductive transfer can effectively minimize the "s" value.  Because of this, water cooling is also best with copper, large surface areas of transfer, and higher delta temperatures.
-edit-
Please note, that the decrease in s for water cooling is allowed to be over a much large area.  This is why you don't see a single heat pipe cooling on big coolers, but a water loop can reasonably support surprisingly long radiator passes before the increase in radiator residence, and thus energy transfer, does not have a functional influence on performance.
-edit-


To a point nobody is likely to make; why do we need fans at all then?  The equations are all based upon T2 being a constant ambient.  If fresh air is not blown by the surfaces, the "ambient" temperature will rise, leading to poorer CPU temperatures.  You could use the same equation for a passive cooler, but the T2 now requires calculation of energy transfer by conduction and convection.  This is why "silent" systems often have high temperatures, and must have low power chips.

As another note, this is grossly oversimplified.  The heat transfer in a simple air cooler is CPU-IHS-thermal paste-cooler body-fouling layer-ambient air.  Showing that combined equation is...painful.  Let's say this, I come from the point of authority because of passing the FE exam, and 4 years of hell.  Should anyone want to argue I suggest a cross and a thermo book.  The latter for content, and the former for once you start speaking in tongues and want to slay the book.


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## MrGenius (Sep 3, 2017)

lilhasselhoffer said:


> Let's take a look at something else new.  Nickel plating.  Why would you do this?  The secret here is also geometry.  If your increase in surface area (A) is greater than your decrease in q, then you're still going to transfer more energy.  If you have a thin enough coating, you could cover a copper heatsink in plastic and it would still transfer more heat.









Nickel _plating _is just for looks. Why/what/how/where? Because copper oxidizes when exposed to air. Thus becoming less visually appealing. Nickel plating prevents that. Nickel is relatively cheap, easy to use for such purposes, provides a long lasting/durable protective layer, and has relatively "good" thermal conductivity. Making the practice of nickel plating copper heat sink components less stupid than it could be. Plastic coating a copper heat sink? No...actually...no...forget it...there's so much wrong with that I'm just going to pretend you didn't say it. In any case...you're talking about a microscopic layer of whatever increasing surface the area by a totally insignificant amount possibly yielding an equally insignificant amount of additional heat transference. Insignificant x Insignificant = Insignificant² = End of story.

Do go on though. Everything else you're saying seems to have a solid basis in reality.


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## micropage7 (Sep 3, 2017)

copper is good but it looks easier to get oxidation than aluminum, aluminum is cheap and i guess although copper is better, aluminum wins on price with good performance


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## eidairaman1 (Sep 3, 2017)

micropage7 said:


> copper is good but it looks easier to get oxidation than aluminum, aluminum is cheap and i guess although copper is better, aluminum wins on price with good performance



My cpu cooler, Id love an Adonized/nickle plated full copper unit but they havent


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## jboydgolfer (Sep 3, 2017)

I know some of the "elite" pc enthusiasts love the 100% copper look, but i find it gaudy. I never liked yellow gold either, but obviously thats a preference of personal tastes. Anodized imo is best aesthetically.


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## Designer (Sep 3, 2017)

Thanks lilhasselhoffer for bringing the equations and math into the discussion.  I was too lazy to go back into the books to get the details.  Looks like you are working with the numbers on a daily basis.
Cool Stuff!


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## eidairaman1 (Sep 3, 2017)

jboydgolfer said:


> I know some of the "elite" pc enthusiasts love the 100% copper look, but i find it gaudy. I never liked yellow gold either, but obviously thats a preference of personal tastes. Anodized imo is best aesthetically.



Lol I'm not 133+ because I don't have a core i7 7700


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## FordGT90Concept (Sep 3, 2017)

Copper is a better conductor but it isn't as rigid as aluminum which, in practice, means lower fin density.  This is why most HSFs have a copper contact with the CPU and potentially copper heat pipes.  The fins and greater assembly is aluminum.  All copper heatsinks usually have fins many times thicker than aluminum heatsinks.  The best, is therefore, a combination of both.

The thing HSF manufacturers aren't doing anymore that they should be doing is stamping dimples into those aluminum fins to reduce drag.


Edit: Here's an everything-is-equal study of copper and aluminum:
https://www.ecnmag.com/article/2010...erent-heat-sink-materials-cooling-performance

TL;DR: If only looking at thermal dynamics (not weight and not cost) and everything else is equal (especially surface area), copper will be better.


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## Designer (Sep 3, 2017)

That is a great study.  It is interesting how the copper k value that is twice as high as aluminum only produces a 21 percent increase in overall performance.  That result demonstrates the law of diminishing returns.  Also, the study demonstrates how the overall performance is dependent on the velocity of the air passing by the fins.  Back to the "weakest link" problem of getting the BTU transfer to the cooling airstream.


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## FR@NK (Sep 3, 2017)

I've been considering getting one of these waterblocks that have a base made out of silver.


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## lilhasselhoffer (Sep 4, 2017)

MrGenius said:


> Nickel _plating _is just for looks. Why/what/how/where? Because copper oxidizes when exposed to air. Thus becoming less visually appealing. Nickel plating prevents that. Nickel is relatively cheap, easy to use for such purposes, provides a long lasting/durable protective layer, and has relatively "good" thermal conductivity. Making the practice of nickel plating copper heat sink components less stupid than it could be. Plastic coating a copper heat sink? No...actually...no...forget it...there's so much wrong with that I'm just going to pretend you didn't say it. In any case...you're talking about a microscopic layer of whatever increasing surface the area by a totally insignificant amount possibly yielding an equally insignificant amount of additional heat transference. Insignificant x Insignificant = Insignificant² = End of story.
> 
> Do go on though. Everything else you're saying seems to have a solid basis in reality.




You miss the point.

The process for creating that Nickel coat is generally electro-deposition.  The copper is cleaned chemically (acid bath), washed in water, then submerged into a solution of aqueous nickel salts.  As to which one, I cannot speak.  A Nickel electrode is then charged, so that the Nickel ions inside the solution precipitate onto the charged copper surface, and more Nickel is brought into solution from the sacrificial electrode.

From a purely mechanical point of view, you are covering the copper with a much poorer conductor.  This would, inductively, seem to be idiotic.  Yes, the goal is to create a sacrificial layer that doesn't oxidize well, but as a side effect the performance is not significantly influenced because the very thin layering is counteracted by the relative increase in surface area.



As far as plastic, it's the exact same concept.  The difference is that instead of a sacrificial coating you'd be functionally sealing off the copper from oxidation.  If this is somehow a foreign concept, I'd suggest you look into magnetic wire.  If that doesn't work, I'd like to ask if you've ever been skiing.  The metal poles are often coated in very fine plastic layers.  Believe it or not, getting a tongue stuck to one of them is actually easier than getting it stuck to a large metal pole.  I'd prefer not to explain why I know this, but let's just say I won the bet and the person who thought I was crazy wound up rather distressed.


Doing the math here is a thankless task.  Everybody wants it proven out, then wants to argue when the concept is beyond what they think.  Let's just do a thought exercise.  The coating material has half the k value of the substrate.  The dT value is immaterial, because it is constant.  This means that to have the same q value the coating must have a k*A/s value which exceeds that of the uncoated sample.  In our thought experiment, that means A/(2s) is what you need to aim at.  If your geometry is good, you'll note that there aren't a whole lot of shapes where surface area has that quick of an uptick.  This is why the coating must be very thin.

From a giggles point, what processes actually do this?  Vapor deposition, electro-deposition, and some chemical sprays.  Plastic is largely a lump of material with longer chain polymers, making it difficult to do this without something like spray paint.  Not only all of this, but cost is key.


-edit-


FordGT90Concept said:


> Copper is a better conductor but it isn't as rigid as aluminum which, in practice, means lower fin density.  This is why most HSFs have a copper contact with the CPU and potentially copper heat pipes.  The fins and greater assembly is aluminum.  All copper heatsinks usually have fins many times thicker than aluminum heatsinks.  The best, is therefore, a combination of both.
> 
> The thing HSF manufacturers aren't doing anymore that they should be doing is stamping dimples into those aluminum fins to reduce drag.



I was hoping somebody would start this.

Why are Intel's heatsinks designed the way they are?  Why not just put an accordian press on a copper sheet and call it a win?

Welcome to the world of machining, and production.


Note something fun about Intel, their cooler design sucks because it is designed to be easy to manufacture cheaply and support barely below thermal throttling.  The copper core provides adequate transfer from IHS to the aluminum body.  The aluminum body is a cast piece, of relatively low quality and mechanical properties (seriously, try to bend one the fins and you'll snap it).  Voids and impurities in the aluminum mean that heat transfer is OK, but it functionally means OK is all you get.

Copper is miserable to machine.  Intuitively, you'd think that such a soft metal would be easy, but you would be misunderstanding what a lathe and mill do.  Machining equipment actually chips away at the surface of metals, so a more maleable material requires special care.  To compensate for this, you've got greater machining times, specialized tooling, and none of this even mentions that the copper is insanely priced because it requires degassing for its best thermal and mechanical properties.

One last bit, the dimples aren't what you think.  In a golf ball the dimples reduce drag, but you're looking at a airflow that is definitely chaotic instead of laminar.  In a cooling fan, you've got a laminar flow of air.  The flow is not extremely high volume or high speed, which means you don't stand to gain a lot from creating a turbulent flow to minimize the fouling layer.  There may be some gains, but we're talking so small at the common usage scenarios that the added manufacturing cost and complexity would literally be immeasurable for 99.99999% of consumers.  This is the same reason I laugh when people building a water loop ask why the water isn't warmer after flowing through the CPU block, when their sensor is only calibrated to at most +/-1 degree C and they're got a sub 300 watt TDP system.  It's not that there is no change, but the change is so miniscule as to be immeasurable.





FR@NK said:


> I've been considering getting one of these waterblocks that have a base made out of silver.




Please, don't.  At least not for the purpose of better performance.

Check that table I linked to on page 4.  The difference between the two materials is 29 (copper = 401, silver = 429).  That is a 7% difference in k values.  If the price difference is so minute, then it would be worth it.  In practice, you're looking at a system that still relies on a copper radiator to transfer the heat into the surrounding environment, correct?  

The math is a pain, but at steady state:
q(CPU)=q(radiator)  
Nominally increasing q for the water block isn't going to do you much good without either changing the material of the radiator, or making sure it is large enough to overcome the material difference.  At that point, you're investing a heck of a lot of money for a 7% difference.  I'd spend that money on higher static pressure fans if I was in your shoes.

If your goal is minimum maintenance, I'll eat my words.  Silver salts don't form well, and oxidation of silver generally requires relatively acidic (sulfur based acids if memory serves) environments.


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## FordGT90Concept (Sep 4, 2017)

http://www.frostytech.com/articleview.cfm?articleID=2461

Dimpled heatsinks are cooler than the competition (a full degree Celsius) with less noise (4 dB quieter than second place).  On Intel (hotter) test, the temp was about the same (still the lowest) but it did it with almost 10 dB less noise.

In that HSF design, they used copper heatpipes and everything else aluminum.

Stamping dimples into the aluminum isn't terribly expensive (just one extra step in production).  The problem is that consumers don't realize how much of a difference that makes.  When people see a non-dimpled HSF for $50 and a dimpled HSF for $55, they tend to buy the $50 model because they don't realize how large of a difference that $5 makes.  It doesn't help that stores like Newegg doesn't make it easy to find dimpled HSFs.


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## lilhasselhoffer (Sep 4, 2017)

FordGT90Concept said:


> http://www.frostytech.com/articleview.cfm?articleID=2461
> 
> Dimpled heatsinks are cooler than the competition (a full degree Celsius) with less noise (4 dB quieter than second place).  On Intel (hotter) test, the temp was about the same (still the lowest) but it did it with almost 10 dB less noise.
> 
> ...



Let's really dig into this, and try to figure it out.

1) Is the same fan uniformly tested across all testing?  No.  Proof:
*Unless noted, for reference heatsinks with variable-speed fans only the 'high speed' (12V) fan noise measurement is included in the comparison sheet; more detailed results for the low fan speed (~5V) tests reside in each specific heatsink review. ** 'AMD' denotes compatibility with socket 754/939/940 & AM2 processors where applicable. 'Intel' denotes compatibility with socket 775 platform.
http://www.frostytech.com/articleview.cfm?articleid=2461&page=3

2) Are the heatsinks made uniform, namely in finish between the IHS and heat sink?  No.  Proof:
They are listed in the review for each unit, according to their review: http://www.frostytech.com/testmethod_mk2.cfm
Also, the testing is synthetic, so we're looking at a copper block with resistors rather than an IHS.

3) Are they comparing apples to apples?  Nope.  A quick look at these coolers confirms variation in fin density, heat pipe construction, heat pipe size, etc...
The short of this is that instead of 1:1 to demonstrate dimples, you pulled a grab bag of coolers.  No DoE for you, and no conclusions can be drawn.

4) Everything else wrong with your "proof."
My earlier point was to create turbulent flow and reduce fouling layer.  They reference the same effect, then add that this requires greater flow velocity and pressure.  Apply the same better fan, and you change the results of the original test.
Changes in design.  You can't say dimples create a better transfer, and change geometry, fin density, and construction.  In a DoE (Design of Experiment) you test one factor to determine influence, and this is definitely not that.
Performance is not really different here.  Do the math.  Variability in a dozen areas means your error factor is larger than a few degrees.  Despite this, you claim it as proof.  It's just not a conclusion.
etc...


Again, in practice there is no difference. If you read the papers by these people they aren't talking about absolute heat transfers in a heat sink.  They're determining how the variation of dimples will influence the heat transfer rates.  If you look at the sources there is exactly one citation about microelectronics, and half a dozen relating to heat differentials and pressures which would destroy electronics.  They cited it, as a means to create the illusion that they understood the technique, not that he had anything to say about the geometry of dimples on this specific cooler.  Do not mistake this, they only are talking about this cooler.

This is a classic appeal to authority, based upon the fact that most people would only casually read it.  It'd be like me releasing an ice cream, citing a research paper that discussed the optimal process for distributing fat into ice cream, and then demonstrating I have the best and richest ice cream (because I read the research paper).  What I don't tell you is I have an extra 3% milk fat, and that the judges had tasted different flavors from all entrants.  Maybe the judges like my chocolate because of a bias for it instead of the flavors from the other contestants.

No.  Bad science, and no conclusions can be drawn.  Good try though.  You're looking at one article, one cooler, and the one conclusion it performs better.  Why is not answered, nor asked.  A BS proposal for dimples is discussed, then dropped.  You read into it, created a link, and made a false conclusion.  Read again.  The conclusion is that a heat sink has dimples, and that experimentally it performs well.  You can't say it is because of the dimples.


----------



## Totally (Sep 4, 2017)

MrGenius said:


> Nickel _plating _is just for looks. Why/what/how/where? Because copper oxidizes when exposed to air. Thus becoming less visually appealing. Nickel plating prevents that. Nickel is relatively cheap, easy to use for such purposes, provides a long lasting/durable protective layer, and has relatively "good" thermal conductivity. Making the practice of nickel plating copper heat sink components less stupid than it could be. Plastic coating a copper heat sink? No...actually...no...forget it...there's so much wrong with that I'm just going to pretend you didn't say it. In any case...you're talking about a microscopic layer of whatever increasing surface the area by a totally insignificant amount possibly yielding an equally insignificant amount of additional heat transference. Insignificant x Insignificant = Insignificant² = End of story.
> 
> Do go on though. Everything else you're saying seems to have a solid basis in reality.



What he is saying is true but the example he gave was just terrible.


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## Designer (Sep 4, 2017)

In the HVAC industry, there are many manufacturers of coils that proclaim that the "wave fin" (or some other hyped up name) improves heat transfer by creating turbulence.  This technique (and sales pitch) have been used for over 50 years.  I am assuming that one or some of these manufacturers actually have test data (with waves versus without waves) to substantiate their claims.  Some of the manufacturers do hold patents on their fin wave geometry.

Try this google search:
"Do wave fins on a coil improve heat transfer"


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## FordGT90Concept (Sep 4, 2017)

@lilhasselhoffer knock yourself out (especially section 3.2): https://theses.lib.vt.edu/theses/available/etd-12182008-161703/unrestricted/Dissertation.Elyyan.pdf


			
				TLDR said:
			
		

> Afansayev et al. [1993] studied the application of shallow dimples (δ/D =0.067) on flat plates on pressure drop and heat transfer for turbulent flow.  They reported a 30-40% increase in heat transfer with negligible increase in pressure drop.


The fan blades should be dimpled too.


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## Asuredawn (Sep 4, 2017)

Mythbusters did a show on how dimples (like in golf balls) reduce resistance on a vehicle. The conclusion was it's plausible. Dunno how that'd relate to coolers, but I know if there's evidence of a difference there, it probably makes a difference in cooling as well.


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## FordGT90Concept (Sep 4, 2017)

http://www.motoiq.com/MagazineArticles/id/2742/pageid/5276/ask-sarah-dimples-on-cars.aspx


> Back to cars and more specifically the 2004 Lexus LS430 which received a lot of attention from its Super Bowl ad that turned the LS upside down in a wind tunnel to reveal the dimpled panels on the undercarriage.  Dimpled panels on the underbody are actually becoming quite the norm from the Mercedes Benz CLS to many Porsche, Volkswagen, and Audi models, among others.  *These are typically used on an undercarriage where there is a zero pressure gradient geometry, more commonly referred to as flat plate type flow.*  The flow in this environment doesn't tend to separate since two dimensional instabilities such as Tollmien-Schlichting (T-S) waves cause the flow to naturally transition to turbulent without needing any type of vortex generators.  T-S waves carry a certain frequency that amplifies in a range of Reynolds numbers.  Environmental disturbances, typically sound, cause wave instability and transitions the flow from laminar to turbulent.  Car manufacturers may put dimples on the underbelly pan, airflow dams, or other parts of the cars to reduce wind noise and drag. *Additionally these dimples can also help strengthen the panels.*


MythBusters took the theory to the extreme.


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## lilhasselhoffer (Sep 5, 2017)

FordGT90Concept said:


> @lilhasselhoffer knock yourself out (especially section 3.2): https://theses.lib.vt.edu/theses/available/etd-12182008-161703/unrestricted/Dissertation.Elyyan.pdf
> 
> The fan blades should be dimpled too.



Demonstrate your conjecture.  Demonstrate how it works in the application you have described.  I'll wait, because nothing thus far has done so.  In order to do that, you'll have to find data that I'm not sure exists.  Namely, data where all other items are held constant and testing is done in conditions comparable to what a CPU cooler would see.  No research paper, no variation in material, and no variation in design because a 1:1 is not produced for consumer products.  I know I'm asking for the impossible, but you bear the burden of proof when you claim that dimples automatically make a cooler better.  I have the much easier job of poking holes into the argument.


Mathematically, a turbulent flow exposes more area to the transfer material (and the dimples increase surface area too).  Heat transfer also occurs by both conduction and convective influences, effectively boosting q.  In theory world, this means a maximum of 30-40% better q values because the A value is increased.  I say theory world, because the paper in question did not focus itself on practical applications demonstrable in a CPU cooler.  This is the issue with drawing a conclusion based on poor arguments, which derive themselves from a poorly interpreted appeal to authority.

Now in the real world (read: messy and prone to us humans borking things pretty badly), let's consider doing this.  You are a brisk business, and sell about 100,000 units of a cooler per year.  Said cooler requires only 30 fins per unit.  That means an additional 3,000,000 processes per year.  

I'll give you a press which can produce 2 parts per stamp, because any more than that and the labor of loading and unloading starts to add up.  You need 1,500,000 cycles.  The average laborer does 2000 hours of work per year, which means that if this takes an entire shift all year round then you've got to have 750 cycles per hour, or 12.5 per minute, or a cycle every 4.8 seconds.  Pay said laborer the equivalent of $30,000 per year.  Now, purchase the press.  You're looking at an initial investment of maybe 250,000 dollars.  Consumable materials, including the dies for the stamping, are another 30,000.  Let's just put maintenance due to wear at 45,000 per year (swag, but based upon oil, minor fixes, die work, and other factors).  You've got $355,000  invested into adding dimples to your 100,000 units sales.  A net cost of $3.55 per part, without even factoring in inefficiencies and down time.  You're looking at an increase in cost of about $5.00 per part once the increase in infrastructure is actually factored in.  

Now, build in profit.  You produce the parts, and sell them to a distributor with a margin to make this work profitable.  The distributor adds their margins, before selling it to a retailer.  That $5.00 cost was increased to $6.00 by you, $12 by the distributor, with $24.00 by the time you buy it.  If you have a cooler that costs $30 to buy, with a $24 upcharge because of an additional process, you have functionally 200% costs for a 140% performance.  


Now, let's look at your one example.   The cooler is at most 1 degree C cooler than its competition.  The noise level is incomparable, because the fans aren't certified to be uniform.  Benefit of the doubt, a 12% increase in relative cooling.  How much is the increase due to change in effective area, convection, and changes in material thickness (s)?  I can't determine any way to tell, but if you see something I'm missing I'd gladly acquiesce to ignorance in order to understand your perspective.

Circling back, walk me through this one more time.  Exactly why would you suggest we add dimples?  In experimental conditions, with fine controls that are all but impossible in regular manufacturing, they demonstrated a 30-40% increase in q with a higher pressure drop.  In practice, you demonstrate negligible performance gains with a test that is eight years old.

By this same logic, we should really use silver instead of copper, because that extra 7% k value will make a difference.  It's odd, because you hit the nail on the head earlier, aluminum is used in fins not because of its performance but because it is less costly and easier to manufacturer.  Yet in the case of dimples, you've reversed your opinion.  A minor, demonstrated by a single degree in ideal conditions, performance difference has a large associated cost.  

As a note, the cooler in question was Japanese only.  A country notorious for spending vast sums of money on perfection, rather than having a reasonably priced 80% solution.  I can't find any pricing information, but I'd conjecture that was the case here.  Again, if you can prove me wrong I'd gladly acquiesce to ignorance.



-edit-
As to the math again, welcome to heavy physics.  Namely, the world where scientist acquiesce to their models not being an accurate prediction of the world.  

Read your own section please, because while rather wordy, it spells things out....clearly if you understand the background.  To the layman, this is all insanity:

"In an effort to disrupt the boundary layer in continuous fins, perforated fins have also been studied where a pattern of spaced holes are formed in the fin material before the fin is folded into a U-shaped flow channel (Webb and Kim [2005]). The perforated fins produce little heat enhancement in the laminar flow regime and a moderate one in the turbulent regime (Webb and Kim [2005]). Fujii et al. [1988] studied a new type of perforated fin, where the heat exchanger is constructed with surfaces using enlargements and contractions forming a trapezoidal shape. Fujii et al [1988] covered Reynolds number flows less than 3000. They reported that the heat enhancement from the fin surface is due to the secondary flow induced by the suction and injection through the perforations, and due to the frequent boundary layer interruptions at each contraction part."

Note:
1) The perforated fins produce little heat enhancement in the laminar flow regime and a moderate one in the turbulent regime (Webb and Kim [2005]). 
2) Fans produce functionally laminar air flow
3) Dimples generate turbulence, assuming some high velocity air
4) The cited Reynolds numbers are high.  High as in not applicable to our geometries high.
5) The cited paper, http://heattransfer.asmedigitalcollection.asme.org/article.aspx?articleid=1443782, deals with tube heat exchangers and surface roughness

To put a lot of science very briefly, it has been stated that you can increase heat transfer by turbulence.  You can generate turbulence in low density and low speed fluid flows vie discontinuities.  Even despite this, the influence ranges from little to moderate.  Given that we aren't talking huge temperature differentials, this equates to low gains in practice.

The funniest part, none of this matters.  The Reynolds number for a chord length of 15 cm, with a 100 CFM fan, whose linear velocity is 3.5 m/s, with a kinematic viscosity of 1.5111E-5 M^2/s, is 34,743.  Way outside the range of the 3,000 cited.

Again, the papers are not looking at the same thing you are (Reynolds calculator here http://airfoiltools.com/calculator/....15&MReNumForm[kvisc]=1.5111E-5&yt0=Calculate).  If you could slow the flow, increase the chord length, or increase kinematic viscosity we'd be on the same page.  As this stands, you're still not applying the research in a constructive manner.  

While technically correct, you're spending  a huge amount of effort to find the last 2% of returns.  It isn't done, because it isn't rational.  If you want to argue that, then please build your own superior cooler for the same price.  I'll vote with my wallet, but I'm not paying 200% of the price for 140% of the performance.  I will however agree that thicker fluids (read: liquids) have this make a heck of a lot of sense.  If you want to build new type of cooler I'm on-board.


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## FordGT90Concept (Sep 5, 2017)

It's not rocket science.  Dimples create turbulence which allows moving air to get closer to the metal (usually shielded because of drag) which facilitates more efficient heat transfer to air that is in motion.  It takes less volume of air to remove the same thermal energy.

Don't need an apples to apples comparison when the difference is so significant in the metrics that matter.  Every time a dimpled heatsink showed up on the market, it outperformed most of its peers (unless they are ridiculously huge in comparison).



lilhasselhoffer said:


> You're looking at an increase in cost of about $5.00 per part once the increase in infrastructure is actually factored in.


Funny.  I said exactly that and I was just guesstimating.  I have no problem spending 10% more on an HSF with dimples.  Problem is, most consumers don't know the difference so they buy the cheaper model.



lilhasselhoffer said:


> "In an effort to disrupt the boundary layer in continuous fins, perforated fins have also been studied where a pattern of spaced holes are formed in the fin material before the fin is folded into a U-shaped flow channel (Webb and Kim [2005]). The perforated fins produce little heat enhancement in the laminar flow regime and a moderate one in the turbulent regime (Webb and Kim [2005]). Fujii et al. [1988] studied a new type of perforated fin, where the heat exchanger is constructed with surfaces using enlargements and contractions forming a trapezoidal shape. Fujii et al [1988] covered Reynolds number flows less than 3000. They reported that the heat enhancement from the fin surface is due to the secondary flow induced by the suction and injection through the perforations, and due to the frequent boundary layer interruptions at each contraction part."


Perforations are holes, not dimples.


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## Steevo (Sep 5, 2017)

Golf Balls. Laminar flow. Coitus Interruptus. Two of these things have something in common.


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## lilhasselhoffer (Sep 5, 2017)

FordGT90Concept said:


> It's not rocket science.  Dimples create turbulence which allows moving air to get closer to the metal (usually shielded because of drag) which facilitates more efficient heat transfer to air that is in motion.  It takes less volume of air to remove the same thermal energy.
> 
> Don't need an apples to apples comparison when the difference is so significant in the metrics that matter.  Every time a dimpled heatsink showed up on the market, it outperformed most of its peers (unless they ridiculously huge in comparison).
> 
> ...



In order.

1) This is rocket science.  Pressure differentials, fluid flow patterns, and thermo are all basic building blocks of rocketry. 
2) No.  Just no.  What you are describing is the decreasing of the boundary, or fouling, layer.  Yes it improves heat transfer, but the boundary layer can never be removed.  It can even be changed in laminar flow by altering the surface finish, fluid flow velocity, and kinematic viscosity of the fluid flowing over it.
3) I don't think you're viewing cause and effect in the same way here.  If I have a crappy fan, I can decrease the performance of any heatsink.  If I have a million dollars I can create a fan with exotic bearings and use a deposition process to grow carbon rod filaments to produce the greatest surface area possible for cooling.  This is engineering, you compromise one thing to get another.  
4) To expand on 3, $5.00 in manufacturing.  You said $5.00 on sale price.  In your example, it's 150% of the price for about 110% of the performance.  If you want a 110% of the price you're looking at $1.00 increase in manufacturing price.  
5) The wording for dimples is obfuscated here.  They initially say perforated fin, then suggest an enlargement and contraction of the surface to create a trapezoidal shape.  No perforation, just shaped metals in a trapezoidal pattern.

I think that covers most of it, but the largest take-away here is that thermo sucks.  Reynolds numbers are a pain, and the abrupt change in mathematics from laminar to turbulent flow makes simple conduction calculations ugly.  All this being said, you've got a delta of 1 degree C for a bunch of extra manufacturing work.  This isn't done because the real world investment into the manufacturing is not paid back in performance.


As an acid test, say you're a start-up.  You can dimple your fan and radiator fin surface.  This buys you a name, even if the profit margin sinks.  You are the 212, or 212+ of a new generation.   The thing is, you can't.  You don't see this because almost nobody would be able to detect a difference.  You'd get better performance results at the same price by optimizing the fan, or simply making the heat transfer surface bigger.  If this is a bit nutty, and it is, then consider how many gigantic densely finned tower coolers exist.  Let's even offer a 10% performance increase.  Aluminum+dimples = 55%, Aluminum+smooth = 50%, Copper+dimples = 110%, Copper+smooth = 100%, Silver+dimples = 115%, and Silver+smooth = 107%.  The maximum performance, all other things equal and assuming enough static pressure, is 15% better.  You'd have to charge so much more for the performance that it would only be viable if money was no object.  At that point, just buy a water cooler and huge radiator.

I understand the arguably demonstrable performance increase of dimples, even if you can't prove it.  I'll even give you that argument.  At the same time, Money talks.  Performance that, in the real world, is arguably not measurable given all the other variables isn't an excuse to spend more money.  If you don't agree, I'm sure I've got a gold plated HDMI cable around here.  Those were supposed to increase SNR....


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## Asuredawn (Sep 5, 2017)

I know I may be nitpicking, but you could stamp and cut in one process, which would make the only difference be in price due to the separate die (if I'm not mistaken).


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## Designer (Sep 5, 2017)

Fields of scientific study (thermo, heat transfer, fluid flow, et al) do recognize the existence of emperical data and events that are not completely predictible nor verifiable, but nonetheless do exist.

example: 

dimples improve performance, 
we understand how and why dimples improve performance (theorize)
only by experiment can we show that "x" size dimples help but "y" size dimples do not help.  
But, We are unable to "prove" by way of an equation exactly how the affects work.
It is this search for a "proof" that has become the subject of many a post graduate thesis. 
Thanks Again


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## lilhasselhoffer (Sep 6, 2017)

Asuredawn said:


> I know I may be nitpicking, but you could stamp and cut in one process, which would make the only difference be in price due to the separate die (if I'm not mistaken).



The "optimal" manufacturing solution here would be to have a coil fed through a flattener, slit to width, run through a large scale stamping press (which would create a repeating pattern along the surface), and then sheared to length in order to spit out a completed part with a near lights-out operation.  This is acceptable because, as the research paper demonstrated, separation and geometry are what matters in dimples.  Cutting and dimpling in a single process is not ideal, unless you're getting metal coil in the width of one surfaces.  At that point, you pay your mill a premium to slit the coil to the desired size.


So the astute would ask why we don't see this.  Let's walk through manufacturing 101.

If you're producing 10,000 units a year this kind of investment is steep.  I'm talking the better part of a decade before you can break even on the price of investment.  Given that these things are generally manufactured where it is cheapest, labor is the cheapest resource.  Reusing old machines is acceptable, and any hydraullic press can be retrofitted to stamp.  The consumables are the die used to press the pattern, the slitter blades, and the shear blades.  All of which will have to be maintained excessively well with aluminum as their input material.  If not properly spaced, or dull, aluminum wipes instead of shearing.

If you were going to go out and propose this to an OEM that does a ton of business, you'd have a case for lights-out operation.  If you're selling these, with the aftermarket consumer in mind, then your sales are extremely limited.  For the benefit of doubt, I'll give you a 100,000 units a year sales figure despite PC sales indicating aftermarket coolers are likely a 10,000 unit a year business in most cases.

Factoring in everything; $250,000 for a press, $100,000 for a slitter setup, $75,000 for a shear, $125,000 for an flattener, and $50,000 for an uncoiler.  Build in a control system, and you tack another $50,000 at minimum (sensors, controllers, etc...).  That puts a lights-out at $650,000 just in equipment.  Layout another $40,000 for infrastructure, and we're at $690,000.  Pay for skilled workers in the third world, and you've got about $75,000 in labor and $25,000 in maintenance based upon amortized costs over a 5 year life cycle with the equipment being phased into legacy product thereafter.  

Let's say your cooler is sold for $75.00.  Let's say that there's only a distributor, so the cost to distributor is $37.50.  You're a manufacturer, so the most you're making is 10%.  That means every cooler nets you $3.75.  At 100,000 units a year, your gross profit is $375,000.  This means in the first year you can't make any money (690,000+75,000+25,000-375,000 = 415000 in debt).  In year two you still lose (415,000+75,000+25,000-375,000 = 140000 in debt).  In year 3 you make some money (140,000+75,000+25,000-375,000 = 135000 in profits).  

Now you've got a refresh to the sockets.  If you're lucky, a minor change can be made.  If you're unlucky the process starts all over again.  The stamp is salvageable, the shear is reusable, and the slitter can be adjusted.  Of course, the fins are likely the cheapest part of the cooler, given that heatpipes and contact plates are toleranced much tighter and will need to be adjusted for any significant socket change.



TL; DR
Intel flipping sockets is bad for consumers, and manufacturers (worse, when you factor in AMD's relative decline in the last decade).  They are OK with it because their coolers are a mess, with performance meant only to keep everything just below thermal throttling.

Even if we wanted to make all fins dimpled, the associated cost and lack of substantial (read: not worth the investment to performance ratio) benefit is where the rubber never meets the road.  While it is fine to conjecture about how much cooling could be better, all demonstrated facts point toward dimpling being a great paper idea but not worth the effort.  This is similar to the paper gains of silver and more exotic materials.  Added costs vastly outstrip benefits.  As was put earlier, diminishing returns poisons this idea.

-Edit-


Designer said:


> Fields of scientific study (thermo, heat transfer, fluid flow, et al) do recognize the existence of emperical data and events that are not completely predictible nor verifiable, but nonetheless do exist.
> 
> example:
> 
> ...



I don't disagree.  The converse is true in this case though.  Mathematically the dimples "should, ideally" produce 30-40% better heat transfer.  I will not argue that, because I can't.  The provided empirical evidence, which is lackluster in proving or disproving anything, is that the difference is at best 1 degree Celsius in a real world application.  

My point is proof may exist.  Papers may confirm the theory.  The provided data is insufficient to pull any conclusions, and trying to fabricate them because of a single article with a tenuous link to a research paper is not a profitable project.  This is combined by the research being done in conditions dissimilar to those found in coolers, and the comparative coolers not being made uniform in any way.

Basically, if you double the amount of fins, an aluminum cooler could (theoretically) match that of a copper one (all other things being constant).  In this case, there is no correlation between performance, geometry, material construction, and other very poignant variables.  It's just a random sampling of available consumer products.  That's useful for purchasing decisions, but not proof of anything but product A being better than product B for an unknown reason.


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## Designer (Sep 6, 2017)

I think our observations here on this forum confirm that consumers make product decisions based on: hyped up literature, peer pressure, personal bias, gut feeling, etc, etc.  Most product decisions are not based on rational analysis and research.
The irrationality of purchases is what fuels the manufacture of products that would otherwise not make sense or be justified.
I guess that's the study of marketing .  "Let's convince em why they need this"
Thanks


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## FordGT90Concept (Sep 6, 2017)

lilhasselhoffer said:


> I understand the arguably demonstrable performance increase of dimples, even if you can't prove it.  I'll even give you that argument.  At the same time, Money talks.  Performance that, in the real world, is arguably not measurable given all the other variables isn't an excuse to spend more money.


What's the benefit of hardware running cooler and quieter?  I see dimpled heatsinks as sitting between traditional heatsinks and water cooling.  Dimpled heatsinks could also be used at the high end of water cooling for the same reason they're useful in air cooling.

I think if dimpled heatsinks were widely available, they'd be the gold standard in server farms because they should theoretically reduce operating costs (fans require fewer amps).




Designer said:


> I think our observations here on this forum confirm that consumers make product decisions based on: hyped up literature, peer pressure, personal bias, gut feeling, etc, etc.  Most product decisions are not based on rational analysis and research.
> The irrationality of purchases is what fuels the manufacture of products that would otherwise not make sense or be justified.
> I guess that's the study of marketing .  "Let's convince em why they need this"
> Thanks


Yes, dimpled products failed due to lack of marketing.  Outside of this discussion, how many even realized they existed for computers?  There' s effectively 0 consumer knowledge about them and their benefits.  Because of that, most people aren't going to lay down the extra money for them.  Someone would have to build a recognizable brand on the principle.

Definitely a marketing problem and not an engineering problem.


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## eidairaman1 (Sep 6, 2017)

Unsubbing, too many are writing too long a reply, we are not writing books here.


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## lilhasselhoffer (Sep 6, 2017)

FordGT90Concept said:


> What's the benefit of hardware running cooler and quieter?  I see dimpled heatsinks as sitting between traditional heatsinks and water cooling.  Dimpled heatsinks could also be used at the high end of water cooling for the same reason they're useful in air cooling.
> 
> I think if dimpled heatsinks were widely available, they'd be the gold standard in server farms because they should theoretically reduce operating costs (fans require fewer amps).
> 
> ...



1) The hierarchy is already populated.  Solid metal-heat pipe-AIO-custom loops.  An additional $24, tacked onto a $75 product, produces a $99 product.  For that price, why not buy an AIO?  Heck, your "couple of degrees" argument is why AIO coolers even exist when high end air is a step down with a corresponding step down in price.
2) It's not marketing.  This is a question of reward to investment.  If you're looking at a server environment, where space and performance are held above price, then this makes sense.  If you're a consumer, where price is critical, then the extra manufacturing makes little sense.
3) I am...disappointed.  You've extrapolated all of this data from an unrelated study, a single cooler only available in Japan, and a website which literally spelled out that the linked article about dimples was not a direct correlation to performance figures.  I get having a bias, but it's that kind of thinking which led to Bulldozer, Netburst, and other decisions which failed to add context to their "brilliant" idea.  Maybe for a second you should consider your proof.  If it was correct the best computer hardware on the market would be a single mechanical counter.  It can perform only one operation, but it can perform said test as fast as the wheels can be driven.  That sounds silly, but it's what you are arguing.  One cooler, one test with unknown biases, with comparison to more coolers with unknown biases.


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## Designer (Sep 7, 2017)

The first law of thermo confirms that all work (energy) is eventually converted to heat.  The advancement in micro electronics over the last 40 years has jammed a lot of energy (computing power and clock speed) into a much smaller net space (CPU chip).  But when you add the cooling system (fans, fins, tubes, AIO, etc) the gross footprint for that computing power grows significantly.  If space is not a concern (data center floor area, size of server box, etc) then it doesn't make sense to cram chips into cabinets (blades) and compound the congestion by craming servers into rows of racks. From the macro standpoint We found that densities above 75 watts per gross sqft or 2kw per cabinet require rack coolers.  That density driven extra equipment is analogous to the fins, fans, tubes, that are being required in the cabinets for the high speed chips. 
The extra equipment, whether at the macro or micro levels is costly to install AND to maintain over the life of the data center.  Tier 4 data centers need N+1 reliability in the electrical equipment and should have N+2 on the mechanical equipment.  
I can appreciate the desire to avoid overspending for data center design densities AND server design densities.
Thanks


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## FordGT90Concept (Sep 7, 2017)

lilhasselhoffer said:


> For that price, why not buy an AIO?


Significantly less power consumption.



lilhasselhoffer said:


> If you're a consumer, where price is critical, then the extra manufacturing makes little sense.


Well, yeah, no one is going to dethrone AMD's and Intel's stock offerings anytime soon.


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## Designer (Sep 7, 2017)

Remember that discussion about how heat can only flow from a higher temperature source to a lower temperature sink.  And also, the heat starts at the circuit junction level and continues to the outside air where it is finally rejected.
Every time there is a heat transfer from one source to another sink there is a delta T. The first sink becomes the source for transfer to the next sink and another delta T is created.  The delta T's are additive and the result is the junction temp must increase to "drive" the heat out of the system.  More on this below.
But, you CAN release heat to a higher temperature sink by adding work to the system.  This is the vapor compression (VC) refrigeration sysrem.  The problem with using VC is the power usage effectiveness (PUE) of a data center gets worse.  The ideal PUE is 1.0.  Meaning all of the electric going into a data center is used for computing.  No electric is needed for heat removal.  10 years ago data centers were designed with an "acceptable PUE" of 2.0.  Every kw devoted to computing required another kw for heat removal.  Factored into that kw for heat removal was the extra energy to operate an N+1 and N+2 equipment strategy for a Tier 4 facility. 
Today, designers are being pressured to achieve better overall effectiveness and still maintain high reliability standards. Today, facility designers, server designers, chip designers, and HVAC designers are now working together on the efficient heat removal problem.
Back to the delta T discussion.  A heat removal system (with no added VC work) that can reject the junction heat directly to the outside air will minimize the overall delta T and improve effectiveness.  Also, a heat removal system that utilizes the phase change phenomena in the fluid will also lower the overall delta T and thus improve effectiveness.  I attached a link that just came in from the trade journals.
Interesting Stuff.
Thanks for the Great Conversation.

https://www.nextbigfuture.com/2017/...-of-the-power-of-traditional-air-cooling.html


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## FordGT90Concept (Sep 7, 2017)

That was my thoughts exactly when saying lower power draw.  Water cooling introduces more BTUs to the environment.  Any system that adequately cools with the fewest resources necessary to complete that task is overall better for the entire system.  Efficiency > Power in virtually all things.  If you can make a care almost completely dragless, you can make it go a lot faster with a lot less power.  It makes sense all around.  This is why I'm generally opposed to phase change and water cooling.  Instead of dealing with the system heat and the few watts a fan consumes, you're talking exponentially more power consumption which translates to the room the system is in getting a lot hotter which translates to more environment cooling costs which people often overlook.  Nevermind more points of failure and vastly greater risk of damage should a cooling component fail.  Case in point: friend of mine has a Scythe Mugen on his i7-2600.  Fan died a long time ago.  Didn't matter because the heatsink is fully capable of cooling his processor without a fan at all.  Cooling system that costs nothing operationally.  I'm surprised there isn't more emphasis on that in case and heatsink design.  Case in point: look at the cylindrical Mac Pro.  It has one fan to cool everything and it does it by doing what comes naturally: draw cool air from the bottom of the case and exhaust it at the top.  I think it's long past time to consider a new standard for cases that focuses on passive cooling (orient all heatsinks vertical in the case) with optional active cooling (for high power components).  From a cooling perspective: ATX doesn't make sense.  BTX tried to fix that but I'd argue it didn't go far enough so the standard was largely ignored outside of mass produced machines.


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## Designer (Sep 7, 2017)

Here's a tongue in cheek thought that builds on your recommendation.  Once the servers are mounted in the racks, maybe the need for the case can go away.  Maybe the server manufacturer can work with the chip, rack, and HVAC manufacturers to build a totally integrated box that has super computing capability with well engineered heat removal.
Wait a minute? We already had that!  It was the IBM and Amdahl mainframes of the 60's thru 80's.
The pendulum might be swinging back


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