whats up wit some types of strange heatsinks?

[Lt. Max]

whats up wit some of the heatsinks i see having a copper base and then aluminum round rods sticking out of it, hows that supposed to help? u could make that kinda heatsink at home..

[francisamf]

Copper is an excellent conductor of heat. This is why several HS's use copper as the core. Unfortunately, copper also retains heat more, or is not able to get rid of it as quickly. So great conductor bad dissipation. This is why you would see super CFM fans on many copper heatsinks.

Aluminum on the other hand, while not being a great conductor (it is good enough though for many situations), has better heat dissipation characteristics. That's why you will see aluminum fins on a copper core. Copper conducts heat to the fins, and the aluminum fins get rid of it better.

You will also see silver-, and also tin-coated sinks (for example, Tweakmonster tin-plated ram sinks, Akasa Silver Mountain HS) primarily because silver and tin are excellent heat "dissipators" as well.

Cheers,
F

[Lt. Max]

ohhh, i see :D

ok thnx

[muddocktor]

Originally posted by francisamf
Copper is an excellent conductor of heat. This is why several HS's use copper as the core. Unfortunately, copper also retains heat more, or is not able to get rid of it as quickly. So great conductor bad dissipation. This is why you would see super CFM fans on many copper heatsinks.

Aluminum on the other hand, while not being a great conductor (it is good enough though for many situations), has better heat dissipation characteristics. That's why you will see aluminum fins on a copper core. Copper conducts heat to the fins, and the aluminum fins get rid of it better.

You will also see silver-, and also tin-coated sinks (for example, Tweakmonster tin-plated ram sinks, Akasa Silver Mountain HS) primarily because silver and tin are excellent heat "dissipators" as well.

Cheers,
F

Another one buys into the myths.:p

Actually, the primary reason for the copper/aluminum hybrid heatsinks is cost/weight/machining considerations, not that aluminum "releases" heat better than copper. As this article here (http://www.amdmb.com/article-display.php?ArticleID=105) says, that is a myth. It is a real good article to read for a better understanding of what is going on with your heatsink. The mechanics and equations are over my head, but you can understand the conclusions real easily. If the cost/weight/machining is taken out of the considerations for a heatsink, then copper will always be better for our heatsinks than aluminum. What the manufacturers are trying to do with the hybrid hsf units now on the market is to give you a more efficient heatsink without driving the price up to unreasonable levels or making the heatsink so heavy that you are in danger of breaking the motherboard or socket. I hope this helps in your understanding of the newer style hsf's on the market.

[flounder43]

Originally posted by Lt. Max
whats up wit some of the heatsinks i see having a copper base and then aluminum round rods sticking out of it, hows that supposed to help? u could make that kinda heatsink at home..

Sounds like a Swiftech. This is one of the best performing heatsinks available. Not cheap, though.

Check this...
http://www.overclockers.com/articles500/

flounder43

[Lt. Max]

so does anyone know why the rods instead of fins perform better?

[francisamf]

Sitting corrected here. Apologies for misleading information.

I know I've read that article. Apparently I missed the "false perceptions" part.

Thanks.

Cheers,
F

[nohoy]

Originally posted by Lt. Max
so does anyone know why the rods instead of fins perform better?

im no expert but im pretty sure they would allow for more surface area and that would allow for more cooling possiblities because more surface (on the heatsink) is in contact with a cooler thing (the air)

[nil_esh]

I think that the deal was when you remove the heat source, aluminum will get rid of the heat quicker. But with a CPU you have constant heat so this doesn't apply.

[JigPu]

Originally posted by nohoy


im no expert but im pretty sure they would allow for more surface area and that would allow for more cooling possiblities because more surface (on the heatsink) is in contact with a cooler thing (the air)
Yes, pins have much more surface area than finned heat sinks. However, when using pins, it is hard to get the pins extruded to form a HS. So that is why you tend to see fins rather than pins even though the pins would cool better. It's just hard to stick all those pins into such a small area...

JigPu

[Aesik]

Originally posted by nil_esh
I think that the deal was when you remove the heat source, aluminum will get rid of the heat quicker. But with a CPU you have constant heat so this doesn't apply.

Aluminum doesn't "get rid of the heat" quicker, it has less total energy to dissipate because it doesn't hold as much energy as an equivalent volume of copper.

[nil_esh]

Originally posted by Aesik
Aluminum doesn't "get rid of the heat" quicker, it has less total energy to dissipate because it doesn't hold as much energy as an equivalent volume of copper.

I stand corrected, haven't read that article in a while. I should have said aluminum will cool quicker than copper in the case where you remove the heat source. This happens of course for the reason you stated.

[ButcherUK]

Wow so many people and their mystical Al properties ;)
Anyway another reason for pins I heard was that they have better airflow / turbulence characteristics than fins. Whether this is true or not I couldn't say.

[Patchmaster]

I was wondering about the airflow differences between pins and fins. I would think it rather difficult to calculate exactly what would happen with pins, given the myriad of directions the air can flow. With fins, the air flow should be pretty predictable, though back pressure is probably more of a concern than with pins.

I had considered building my own all copper heatsink using a solid block of copper as the base and solid core copper wire for the pins. I did some calculations on the surface area provided by various combinations of wire diameter and pin density and was quite amazed at how much more surface area is provided by pins. If surface area is your goal, pins are definitely the way to go.