Status
Not open for further replies.
1 - 7 of 7 Posts

#### agentRed

·
##### Registered
Joined
·
426 Posts
Discussion Starter · ·
Okay. Without naming names, I've got in my hands, two different types of compounds.

Compound A's thermal conductivity is: >8.2 W/m °K
Compound B's thermal conductivity is: >350,000W/m2 °C

My question is which compound is better and why? Both are something like 99.5% micronized silver.

#### MunkyPhil

·
##### Registered
Joined
·
1,143 Posts
What you've got there is nonsense. The units you have here aren't the same so a comparison cannot be made. The true unit of thermal conductivity is W/m.K as in compound A. Basically you want this to be as high as possible, it's an indication of how much power can be transfered as heat away from the processor. Don't get this mixed up with thermal resistivity which is the reciprocal of the conductivity (1/Conductivity) - this value should be as low as possible.

What you have for compound B is a heat transfer coefficient (W/m2.K). Again, if you compare two heat transfer coefficients the higher one is the best. Heat transfer coefficients are measured across boundaries and depend on both the materials at the boundary (thermal paste and processor core) so without knowing that all processor cores are made of the same thing you can disregard this value as meaningless and go with the conductivity, which is an indication of how heat passes THROUGH the paste as opposed to TO the paste.

#### MunkyPhil

·
##### Registered
Joined
·
1,143 Posts
Correction: On a basic level the heat transfer coefficient is not meaningless without information about all the materials at the boundary (It is to do with the transfer of heat alone, not the materials themselves) but it cannot be compared to thermal conductivty.

#### Oceanborn

·
##### Registered
Joined
·
151 Posts
ºK = Kelvin Scale
ºC = Celsius Scale

Two totally different measurements....

#### MunkyPhil

·
##### Registered
Joined
·
1,143 Posts
ºK = Kelvin Scale
ºC = Celsius Scale

Two totally different measurements....
Not in the context of these measurements. K = ºC - 273.15 is the linear equation relating the two. Both Celcius and Kelvin scales rise at the same rate so given that the actual measurements in the equations are temperature DIFFERENCES the two are in fact interchangable. Technically though, the Kelvin scale is scientifically accurate. The celcius scale is based on measurements of the solidifying point of water - 0ºC being the ground. It is a scale based on human experience, not on scientific fact.

#### agentRed

·
##### Registered
Joined
·
426 Posts
Discussion Starter · ·
Ah okay. So how am I to compare A and B? I mean...if the units are totally different? I did not make a mistake in copying the numbers down, though, so I know that they are correct.

The only difference I can tell without having proper information, is that one is 99.5% mirconized silver and the other is 99.8%. Not much difference I guess...unless it's a very small amount...

I'm thinking that one is simplified and one is not, hence the 8.2 or whathaveyou. And the absence of the square. To tell the difference between the two, should I try to convert Celsius into Kelvin?

#### MunkyPhil

·
##### Registered
Joined
·
1,143 Posts
I'm sorry agent red but a direct comparison cannot be made. Try doing a search for both heat transfer coefficients of thermal paste and thermal conductivity of thermal paste separately to get an idea of the individual values for other pastes. You'll know what is good or not then - the comparison should be made with Arctic Silver 5 as it is the best.

Or, (for a system in thermal equilibrium) you can take the thermal conductivity and divide it by the thickness of applied thermal paste to give you the heat transfer coefficient (not a good or accurate idea).

1 - 7 of 7 Posts
Status
Not open for further replies.