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copper or aluminum

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January 7, 2007 10:18:06 PM

so if been tring to decide what cooler to get for my proc and i was looking at the zalman 9700 LED and NT. I noticed that one was all copper and the other was copper and alu. so the question popped into my head, which is better?

More about : copper aluminum

January 8, 2007 9:50:01 AM

While that statement is correct it suggests (given the context of the OP) that copper heatsinks are generally better than those composed of copper and aluminium which isn´t necessarily so.
CPU coolers are limited by their weight and since aluminum tends to be a lot lighter than copper, you can have a larger aluminium cooler, which should have a larger surface (and fins that don´t dent like butter) and dissipate heat quite well. Basically it boils down to a function of weight and heat disspipation. I´m not sure how large the aluminum component has to be to be equal to copper though.
January 8, 2007 10:43:55 AM

Given its the same cooler just difference construction, the CU one is better.

This is typical of Zalman, one is a pure copper cooler (the more expensive one usually) and the more budget minded one has a copper core but everything else is aluminum.

Go with the CU one. :D 
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January 8, 2007 11:34:05 AM

the performance of CU is better
the weight of a AL-CU is lower
but AL-CU will do perfect, even if you overclock, a little.
the extra money isn't much, but doesn't give you a price/performance wise extra.
January 8, 2007 11:52:01 AM

Copper pulls more heat from the source than aluminum, but aluminum dissipates heat faster than copper.
January 8, 2007 12:18:30 PM

Look at the Tuniq tower 120, do you really want a heatsink that weighs in at 2kilograms? I dont think so. Dont only look at the material used but the design as well.
January 8, 2007 12:26:06 PM

I've recently had to choose myself and I laid out the cash for the 9700 (after some advice and a few benchmarks from various sites). I've still got to get my e6600 (should be within the next week or two) but I've always prefered to use a copper unit where possible.
January 8, 2007 3:52:33 PM

Quote:
Copper disapates heat better then aluminum.


Aluminum actually dissipates heat better. Copper conducts heat better.

This is the reason most heat sinks use a copper slug and copper heat pipes up to aluminum fins, and not the other way around.
January 8, 2007 4:20:27 PM

Quote:
Aluminum actually dissipates heat better. Copper conducts heat better.

Do you have a source for this info?

-Brad
Anonymous
a b K Overclocking
January 8, 2007 4:41:37 PM

I'm hoping this post will look proper, but I'm not a posting expert. But I do have some expertise to add outside of adding emoticons...

The Cp (heat transfer coeff) of copper is higher than that of aluminum. Copper is superior in all aspects of conducting heat from a high-temp reservoir (your CPU) to your low-temp reservoir (the air).

But, in the real world, the "shape" of your cooler will have a lot to do with how efficiently the heat is moved. For example, you will kill an old-fashioned copper-brass plate-fin radiator with new-fangled aluminum serpentine fin radiator. The heat transfer surface (regardless) of material is fantastically more efficient because of the geometry.

Frankly, I do not know whether the all-copper model will do much better, or not. But my gut says it will be a minimal improvement over aluminum. In 6 months after the dust bunnies have collected, the least of your worries will be the base material of the H.T. surface. I would go for the aluminum myself.

Though copper fins are easier to straighten than aluminum. Aluminum IS brittle, and if you handle the cooler excessively, perhaps copper is the best choice.

FWIW
January 8, 2007 5:01:24 PM

Quote:
Aluminum actually dissipates heat better. Copper conducts heat better.

Do you have a source for this info?

-Brad

At some point I did. But as am am looking for it I'm finding things that are contridicting what i have read.

So at this point I will retract my statement that Aluminum dissapates better until further notice.

But it IS a fact the copper conducts better.
Anonymous
a b K Overclocking
January 8, 2007 5:13:48 PM

Don't be so hard on yourself - :D 

You can sort of make the argument that aluminum is more efficient beause the ability to make a very efficient shape (notice that many factory heat sinks are made of an aluminum extrusion) allows aluminum to trump copper.

But people will pay $$ more for overclockable memory even if they never overclock and other such things. So why not heat sinks?

Just thought of something else. The aluminum is generally a shiny silver color, whereas the copper cooler may look dull in comparison. The aesthetic vote goes to aluminum!
January 8, 2007 5:18:25 PM

Im still waiting for a pure silver Tuniq tower
January 8, 2007 5:26:07 PM

Actually the silver 9700 LED is a copper base plate and fins. It's nickel coated to make it look silver and that's why it's expensive. But no difference on the all copper one.
January 8, 2007 5:40:57 PM

Ok, lets apply some science:

It is true that copper conducts heat better, higher Cp value (as mentioned by someone else) but no-one has mentioned the specific heat capacities (SHC).

The SHC is how much energy one kilogram of substance can absorb to raise it by 1 degree.

Copper has a SHC of 0.31 KJ/Kg/K
Aluminium has a SHC of 0.91KJ/Kg/K (more than double!)

This means that for the same weight of metal Aluminium contains twice as much energy which means it can transfer more energy to the air that passes over it thus keep the processor cooler.

An ideal heatsink i would think is one that has copper nearest to the cpu to transfer the heat away quickly (copper heat pipes) but then changes to aluminium to gain highest transfer of heat to the air (big aluminium fins).

Aluminium is also less dense which means that it can have the same surface area as copper and will weigh less. Higher surface area=more heat transfer.

I think this should clarify the issue.

(I am a chemistry student at oxford university btw)
January 8, 2007 6:10:39 PM

A key thing you have to remember is that this is all in STEADY-STATE:

1) One material absorbing heat into itself better than another means the cpu will stay colder when you first start up but in general operation the temperature in a given spot on the heat sink remains the same over time. i.e. don't count on copper's specific heat capacity to absorb your cpu's heat while you use it, the copper instead has to transport the heat to the fins where it is dissipated by the cooler air.

2) The heat drawn away from the cpu is at the exact same rate as the heat drawn away from the fins by the air (conservation of energy for steady-state systems means conservation of power).

I calculated this for a friend a few years ago and it is very design-dependent, but generally copper will be 5-10% better than aluminum for the same design. So CU is better, just not that much. If you want to get into a real sciencish discussion of how aheatsink should be designed, PM hotfoot.

Jo

Edit: I should also say that the transfer to air is the hardest part since both Cu & Al have very high conductivity, so even though Cu's conductivity is better than Al's by a decent amount (~69%), it does not translate into much extra heat dissipation. Designing a better shape, larger heatsink, thinner fins, better airflow though it are much much more important than Cu vs Al.
January 8, 2007 6:12:33 PM

Quote:
Ok, lets apply some science:

It is true that copper conducts heat better, higher Cp value (as mentioned by someone else) but no-one has mentioned the specific heat capacities (SHC).

The SHC is how much energy one kilogram of substance can absorb to raise it by 1 degree.

Copper has a SHC of 0.31 KJ/Kg/K
Aluminium has a SHC of 0.91KJ/Kg/K (more than double!)

This means that for the same weight of metal Aluminium contains twice as much energy which means it can transfer more energy to the air that passes over it thus keep the processor cooler.

An ideal heatsink i would think is one that has copper nearest to the cpu to transfer the heat away quickly (copper heat pipes) but then changes to aluminium to gain highest transfer of heat to the air (big aluminium fins).

Aluminium is also less dense which means that it can have the same surface area as copper and will weigh less. Higher surface area=more heat transfer.

I think this should clarify the issue.

(I am a chemistry student at oxford university btw)


Finally someone that knows what specific heat is. Also this is why water cooling works so well. The specific heat of water is 1, and an advantage it has over aluminum is that it has a larger mass that also plays a large roll in how much heat can be dissipated

(BTW aluminum has one i not two :lol:  just kidding)
January 8, 2007 6:19:53 PM

Copper heatsinks are heavy (1.5-2 lbs!). That will put significant strain on the motherboard. One thing is for sure, you don't need all that weight bouncing around. So if you intend on transporting/moving the PC a lot, consider getting a lighter aluminum heatsink.
January 8, 2007 6:31:18 PM

A note about the spelling of aluminIUM, which is the correct spelling. Heres something I found

"Aluminium is the IUPAC spelling and therefore the international standard"

So you annoying americans, please spell aluminium correctly in this UK (not america for those of you who dont know) forum.
January 8, 2007 6:38:56 PM

Quote:
Copper pulls more heat from the source than aluminum, but aluminum dissipates heat faster than copper.


Nope. Thermal conductivity of a material doesn't depend on transfer direction. Also, copper is way better than aluminium for thermal conductivity.
January 8, 2007 7:38:34 PM

Quote:
A note about the spelling of aluminIUM, which is the correct spelling. Heres something I found

"Aluminium is the IUPAC spelling and therefore the international standard"

So you annoying americans, please spell aluminium correctly in this UK (not america for those of you who dont know) forum.


I find it quite trivial that we can complain about one little i and correct spelling when we use 2 for to, r for are, u for you, and so many acronyms we need a dictionary just for acronyms.

Anyway back on topic Flewis is correct a combination of both copper and aluminium (now are you happy firefox says I have a misspelled word) would work just fine. Although, the design of the hsf is of much more importance, that’s what you need to look at. One more thing you need to consider is cost, copper is much more expensive. I would say that both hsf you are looking at will work just fine I would just go for the cheaper one. If there is a difference in performance, it will only be a marginal one.
January 8, 2007 7:53:51 PM

Quote:
A note about the spelling of aluminIUM, which is the correct spelling. Heres something I found

"Aluminium is the IUPAC spelling and therefore the international standard"

So you annoying americans, please spell aluminium correctly in this UK (not america for those of you who dont know) forum.


Zalman Tech is a US- and Korea-based company. As such, they make parts out of aluminum - the US spelling since the American Chemical Society adopted the spelling in 1925. (see http://www.jergym.hiedu.cz/~canovm/vyhledav/varianty/ko... and http://periodic.lanl.gov/elements/13.html)

The original spelling was "alumine," proposed by the Frenchman that discovered (I use the term "discovered" lightly) the stuff in 1761. Technically, he was just using that term to refer to the base of alum, which is a Greek word. The spelling "aluminum" was also the original English spelling, proposed in 1807. It wasn't until afterward that the international community decided to mess with the minutiae. Thankfully, the US has managed to maintain its sanity.

On another note, heat capacity is completely trumped by the fact that this is a steady-state problem, as JMecc noted. If you were to completely thermally insulate your computer and only wanted to operate it for a couple of minutes, then yes, heat capacity would be a critical factor in selecting a heat sink material (for the record, at that point, as was alluded to already, water would probably be the sink material of choice - this does play a role in water/fluid cooling, but the only fluid that impacts a dry heat sink is air, and good luck changing its heat capacity. Not that you couldn't, mind you). For any reasonable application of home-user computing, heat capacity plays an even smaller role in functionality than color. And I'm not even talking about aesthetics here. But shape is quite critical. Props to thermistor here.

Also, Niz, small correction: Thermal conductivity can depend on direction of transfer. It just usually doesn't, particularly in metals. If you have an anisotropic material, it can play a factor. Metals are -generally speaking- very isotropic, making this a nonissue for heat sink discussions, but if you look at graphite, for instance, thermal conductivity in-plane is orders of magnitude greater than cross-plane due to covalent vs Van der Waals bonding in different directions. For a nifty application of this property, see here: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Se... (US patent 6797924, if the link doesn't work)
or see here for an explanation: http://electronics.howstuffworks.com/cold-heat.htm

I realize that those links refer more to graphite's electrical properties (which happen to be pretty similar to the thermal properties due to both of them relying on eletron transfer), but in-plane graphite heat transfer is what is making sure that tip stays cool.

I might add here that this particular thread has managed to significantly erode the esteem in which I hold Oxford's science programs. My old advisor went there, but she actually seemed to know her stuff.
January 8, 2007 7:59:33 PM

So here's the KILLER Al vs Cu question...

After two years of fin surface oxidation in a typical household environment, which would dissipate heat better for a given design?

-Brad
January 8, 2007 8:08:04 PM

Quote:
After two years of fin surface oxidation in a typical household environment, which would dissipate heat better for a given design?


Metal will make a very tiny oxidation layer right after exposure to air (way before you buy it) and a bit from you touching it but after that will not really suffer from oxidation inside a case - it is just dust that clogs the airways and prevents heat transfer from being as efficient as on a clean heat sink.

Jo
January 8, 2007 8:15:26 PM

Quote:
I might add here that this particular thread has managed to significantly erode the esteem in which I hold Oxford's science programs. My old advisor went there, but she actually seemed to know her stuff.


Remember NovemberWind that Flewis may be in 1st year or something and that chemistry does not imply any training in Heat Transfer (MecE & ChemE thing), so Flewis still looked at the problem scientifically, just not thoroughly enough to realize the full problem (since this forum is not a job), so it is nice to get discussion going on this anyway.

Jo

Edit: Note I edited NovemberWind to Flevis (see 2 posts down)
January 8, 2007 8:32:04 PM

Yeah, yeah, true enough. I just don't deal well with snooty Brits.

But what do you mean "NovemberWind still looked at the problem scientifically, just not thoroughly enough to realize the full problem?" I'd say my understanding of the problem is fairly good, even if I didn't break down the full thermodynamics of the situation.

Cheers!
January 8, 2007 8:42:47 PM

Sorry Nov I meant Flewis in that last post (I'll go edit) - this would be easier if we had names like Bill & Jimmy instead of ones I have to copy & paste. What I was trying to say is that Flewis was not being a dumbass saying what he did.

Jo
January 8, 2007 8:53:59 PM

I was only joking about the spelling.

But surely if something has a higher heat capacity it can transfer more energy to the passing air. Imagine the material had a heat capacity approaching zero, it would transfer a lot less energy as its temperature would be lowered quicker.

(am just supposing tho, heat sinks arent my specialty and im a 2nd year btw)
January 8, 2007 8:56:06 PM

In the automotive world, copper heater cores and radiators are considered superior to their aluminum counterparts.

My two cents.

Get copper.

But seriously, unless you plan to watercool or do a submersion build (like me), either will probably work just fine.
January 8, 2007 8:59:02 PM

Good some brought about specific heat but less we forget about our friend surface area.

If you got 4 inches of Copper -vs- 1 inch of Aluminum, Copper will win.

Some super sceince guy can help further explain that one and how it relates to specific heat, because i am too drunkard to properly explain, partying for the Ohio State Buckeyes began at noon for the stat of Ohio

GO BUCKEYES!!!!!!!
January 8, 2007 9:04:34 PM

Its temp would be lowered quicker by the passing air if there was no steady-state heat source. In this case, the temperature of the fins stay the same in time (they fluctuate a bit as the cpu is loaded and not, but this fluctuation is very low in the actual fins far from the cpu core). Anyway the heat can be considered to be steady, so the amount of energy it takes to change the temperature of the material doesn't come into play as the material doesn't change temperature. The heat sink has a temperature gradient going from hot at the base to cooler at the fin tips but at each point along this path, the temperature there does not change with repect to time after the initial heat up period which happens during boot up.

Jo
January 8, 2007 10:39:44 PM

Flewis, JMecc already addressed this most of the way, but I'll address this a little bit too, just to add my two cents (because it's fun)

Like JMecc said, since it is steady state, the temperature everywhere stays the same (not IS the same, but STAYS the same - so at the bottom of the HS, it's hotter than at the top, but the top and bottom both stay the same temps the whole time). I'll touch the not-so-steady-state stuff in a second, but it isn't very relevent to real-world applications because the impact is so small, so steady-state is the way to think.

Let's review the energy transfer going on here:
Processor creates heat via wasted energy
That heat (energy) goes through the silicon and into the metal processor housing
***this is a step I'm not very famliar with - anybody know how heat is transfered from the processor to the metal housing? Like, is there a special thermally conductive bonding layer? Or does it just go through air?***
Once in the metal processor housing, a little bit of heat dissipates to the side and into the motherboard/air surrounding the processor. The majority of the heat gets transfered to the thermal compound directly on top of the processor
From the thermal compound, heat goes to the heat sink base
From the base, heat goes to the fins
From the fins (which are there to provide a large surface area), heat is transfered to the air, or other surrounding fluid (Tom's did an article a while back on dunking a computer in vegetable oil, which would in this case substitute for air. You could use other stuff too, but we'll restrict this discussion to fluids only - gases and liquids, but mostly gases)
Then that air is cycled through your computer by the fans

Every one of those materials has a heat capacity, so each one of them is storing some amount of heat through the whole process. But what you have to remember is that you're not just dumping one unit of heat into a mass to dissipate that heat (like the old "Take 4g of quartz at 95°C and drop it into 50ml of water at 10°C inside an insulator. What is the final temperature of the system?") You have a heat generator (processor) and an isothermal fluid (you assume air stays the same temperature, which is generally speaking more or less true, making allowances for air conditioning hysteresis and assuming you're not operating the computer in an insulated room/box, in which case the temperature of the air will rise with time).

But what you have to remember is you're not just dealing with joules (energy), you're dealing with joules/sec, or watts (power). If your processor is spitting off 50W of thermal power (not completely unreasonable if you're pushing things), ALL of that energy that you're throwing out is being dissipated. Now, sure, the more power your processor puts out, the hotter things get, but unless the temps get too hot for the processor to keep going, things are always going to level off at some sort of steady-state dynamic equilibrium. So the vast majority of that 50W is going through that chain of energy transfers listed above and coming out the back of your computer as hot air.

Back to heat capacity now: Let's assume your heat sink has an ultra-high heat capacity. What happens when your processor fires up and the heat sink is at room temp, along with the air? The heat sink will absorb a boatload of joules of energy as the processor warms up. The heat sink will rise slowly in temperature because it is able to absorb a lot of energy per rise in temperature, though it will also dissipate a little bit of heat to the ambient environment as it rises in temperature. As it gets hotter, it will dissipate more heat, because it has less heat capacity remaining, and the temperature difference between it and the air is greater, thus heating the air more and sending more heat off from the surface. Eventually, the heat going into the heat sink will balance out with the heat coming off the heat sink into the air - about 50W. If the heat sink were to absorb more energy, it would get hotter. But this would also make the air take heat off more quickly, so it would cool faster. So anyway, our high heat capacity material is now holding a boatload of joules, but the heat dissipation is still at a constant rate.

Now consider the opposite - a low heat capacity material:
Just like with the high heat capacity material, as the processor warms up, the heat sink packs away some of the joules. But because the heat capacity is low, it can't hang on to as many as in the previous example (gets hot faster). At some point, the temperature balances out with the heat transfer to the air (just like the other example), and then the heat sink absorbs no more joules of energy. But just like the high heat capacity material, it's still spitting out about 50W of power into the air.

One item to note is that these two different materials might have different temperatures at which they reach steady state. That really has more to do with the heat transfer coefficients between the thermal mass (heat sink in this case) and the surrounding medium (air). For the record, I don't know what the difference would be between copper and aluminum. A full description of what happens in that scenario is waaaay more than I want to go into here (or remember from my materials kinetics coursework for that matter), but to generalize more than just a little bit, the temperature of the surface of the heat sink needs to be the same temperature as the first layer of air touching it. There's a gradient in the temperature of the air, just like within the heat sink. As air flows past, it takes the heat with it, so the sharper your thermal gradient (i.e. the colder your air is vs the hot temperature of your heat sink), the more watts you're pumping off. Basically, the faster your fans are blowing, the cooler the heat sink stays (duh). And the hotter your heat sink or the colder your air, the faster you are dissipating heat (also duh).

Also, none of anything I've said (except that little color comment) addresses radiative heat transfer at all. Certainly, thermal radiation is NOT going to play a major role in computer heat spreaders, but for other things (cars to a minor extent, jet engines or furnace design to a greater extent) radiation can have a far more significant impact. This is because radiative heat transfer has a very tiny coefficient, but is proportional to T^4, so as the temperature differences grow, or temperatures rise in general (think 2^4-1^4=7, so a temperature difference of 1K is proportional to 7 from 1K to 2K radiatively, but 1001^4-1000^4=4E9, so the radiative heat transfer portion from 1000K to 1001K is proprtional to 4 billion) then the radiative portion becomes more significant in equations and of course application.

I hope I've made this somewhat clear (if rather involved) already, but to end, I'll address the example you propose. If the material had a heat capacity approaching zero, it would simply equilibrate to the surrounding environment. Imagine you have a little magic ball that creates energy at a constant rate (again, we'll say 50W). Now take that ball and completely enclose it inside another ball made out of another magic material which has heat capacity approaching zero. That 50W has to go somewhere. After steady state kicks in, the surface of that exterior ball is going to be giving off 50W. That DOESN'T mean that the exterior ball is going to be the same temperature throughout, nor that it isn't going to get hot inside. Both of those factors depend on heat transfer coefficients, both inside the material and between materials. But at the end of the day, no matter what, that exterior ball is going to give off 50W of power.

Oh, by the way, for the few of you left reading this massive post, heat capacity is a function of temperature. And as you approach absolute zero, you also approach zero heat capacity (part of the problem with actually hitting absolute zero - unable to transfer energy away to get to a perfect crystalline state). Now you can go take this wonderful wealth of newfound information and go cry in a corner because nobody else cares.
January 8, 2007 11:03:56 PM

Way to explain it NovemberWind! The lower heat capacity material will reach steady-state faster than a higher capacity one. Either way this will happen quickly (unless your heat sink weighs 100lbs) so it is not important.

Jo
January 8, 2007 11:34:59 PM

Terrific post, thanks. If I read everything correctly then one of the "take home" items would be that a material with lower SHC, such as copper, should actually be better able to react to changes in power (quicker to resume equilibrium at a preferred temperature once fan speed kicks up in response to core temperature readings) since it stores less energy? Or is that not a good assumption?

There's a fair amount of hysteresis when you look at curves comparing core temperature and CPU fan speed in a QST setup. I'd think that anything that lessens the lag is a good thing.

-Brad
January 9, 2007 3:45:11 AM

Quote:
If I read everything correctly then one of the "take home" items would be that a material with lower SHC, such as copper, should actually be better able to react to changes in power (quicker to resume equilibrium at a preferred temperature once fan speed kicks up in response to core temperature readings) since it stores less energy? Or is that not a good assumption?

There's a fair amount of hysteresis when you look at curves comparing core temperature and CPU fan speed in a QST setup. I'd think that anything that lessens the lag is a good thing.

-Brad


All other things being equal, what's really driving your equation is the thermal conductivity. And really, another thing I didn't address at all is the thermal conductivity between two connected materials. If you aren't making things out of a single mold, you have to connect them together. There are three basic material connections you can make - solder, braze and weld. Then there are other things that you can do, like gluing, riveting, or just snapping things together. Good luck welding copper, so really the best thing you can do is braze. Any of those other materials connection methods (including solder) will wreak havoc with the thermal transfer. A copper-to-copper braze won't really impact the thermal conductivity too much because the brazes you would use would be silver-copper based. I'm not familiar with what brazes (and I'm only assuming that they actually are brazed) are used for Cu-Al connections. Personally, just from a materials connection standpoint, I'd rather use a single block of copper rather than a Cu-Al composite heat sink. Although honestly, in practice I imagine you'd only be talking about a percent or two differential between the two. But if it looks like there's some sort of crappy material connection job between materials (even if it looks like they riveted copper to copper) steer clear.

But back to your question. I was thinking initially that heat capacity wouldn't really figure into it, but then I delved into my old copy of Transport Phenomena in Materials Processing by Poirier and Geiger (dry as the Sahara, mind you). What you're getting into with this question relates to the Fourier number, which relates to the shape of the object. It's a dimensionless constant which equals (for plates):
(thermal conductivity*time)]/(density*heat capacity*thickness^2)

Now, you can get a Fourier number from a table if you have a Biot number (=heat transfer*thickness/thermal conductivity) and a relative temperature (temp-final temp / initial-final temp)

What this ends up meaning is that time is proportional to heat capacity, so bigger heat capacity translates into bigger (longer) time.

However, something to keep in mind is that time is also inversely proportional to thermal conductivity, so the bigger the thermal conductivity, the lower the time. Going by Flewis's numbers, Al has about triple the Cp of Cu, translating in a 3x longer time. Then the thermal conductivity of Cu is a bit under ~2x that of aluminum. So about a factor of 2 faster time. So what I think you should end up with is a factor of 6 faster response rate in copper vs aluminum. Perhaps this is why the piece that connects to the processor is always copper, even if the fins are aluminum. Along with this, though, remember that steady state is the most relevant stuff. Even with the processor fluctuating, you're not talking about massive changes in heat dissipation. Even when you spike the load of your processor, it takes time (albeit not a great deal of it) for that spike in load to translate into a rise in temp. And mind you, none of what I've discussed here factors in the heat transfer coefficients for copper/air or aluminum/air, which would be somewhat important. I just don't have those numbers.

Still, what I've calculated here (quite roughly, I might add) has convinced me a bit more that copper is the way to go if you really need something to pull heat. But like what has already been mentioned here, shape and material connections are going to trump everything else. And beyond that, factors like how well you apply thermal paste (moreso than what paste you use), what the ambient temperature of your air is, and how fast your fans are blowing are going to drive your equations more than the materials alone, assuming good material connections within the heat spreaders.

Along with this, it's been a long time since I looked at some of these equations, so my handling may be a bit rusty. If any of you spot any errors, please point them out.

And finally, if you REALLY need to move heat, use water cooling where you use a high heat capacity fluid (WAAAAAAY higher than air, which is the normal fluid) to move more heat away at once. Those tend to use all copper tubes anyway, which is good, plus a high heat capacity fluid that you're actively cooling.

PS - your computer will probably work fine without super cooling, so while I obviously find all this thermal transfer pretty interesting, the first question you should be asking is if the slight benefit you can achieve with upgraded cooling vs stock cooling is really worth the price.

PPS - also, don't buy heat spreaders that are painted pretty colors (I don't know how common this is or what reasonably manufacturer would try to do this.....). Just extra potential to add an insulating layer onto your heat sink.
January 9, 2007 11:29:41 AM

Quote:
Copper pulls more heat from the source than aluminum, but aluminum dissipates heat faster than copper.

Nope. Thermal conductivity of a material doesn't depend on transfer direction.
That statement makes no sense, how does that even relate to what I said?

Quote:
Also, copper is way better than aluminium for thermal conductivity.

Um, thats what I said...
!