Installed Zalman 7000A (AL/CU) on a P4 2.4C, temps pretty much the same :(

I.M.O.G. · Nov 3, 2003

Thanks Larva, it was a good read. It also shows that if the CU version could possibly even be better at all, the review shows that it is not better by any considerable amount.

EDIT: This statement previously read this but it didn't convey my meaning: "It also shows that the CU version is not a considerable improvement over the ALCU."

I like how they conclude the article also... They make note of environment variables and the resolution of their test equipment that affect the results. It is a fine reasonable, simple review.

I have a bone to pick however:

The author is clearly mislead in his beliefs about copper and aluminum.

Likewise, even though the overall lower temperature under load, courtesy of better heat dissipation of aluminum nicely fits our expectation, one needs to be very careful not to fall into a wishful thinking trap. There were other factors that could influence the outcome of the tests as well, for example, the air humidity changed during the course of the testing because of a rainshower. Of course, it is possible to repeat everything over and again but by the end of the day, there will always be other variables.

Aluminum does not dissipate heat better than copper under a constant heat load. This is explained here.

It is beat to death here.

In heatsinks that are designed identically, with no difference except in the materials used - a pure copper heatsink will perform better than an ALCU combo.

Cyberwiz01 · Nov 3, 2003

IMOG said:
In heatsinks that are designed identically, with no difference except in the materials used - a pure copper heatsink will perform better than an ALCU combo.

I thought the AlCu and the Cu versions were the exact same design except for the material.

dagamore · Nov 4, 2003

ZL1 said:
see my post above, I have a v-card with a bad fan thats making all the noise it takes to cover everything else so I cant really tell

D

i see what you are saying now, right now i am on a big Zalman kick, i have 6 of their HSF running (2 7000 cu, 4 6000 cu's) and all but one of my systems have the passive zalman NB coolers on them, and all but 2 of my video cards have the Zalman Heatpipe passive cooling on them (damn on board video but since they are passive ly cooled as whell i dont care)

I love how quite my room is again, now i can hear the fish tanks again

, side note all of my systems have enermax 120mm intakes and another enermax 120mm exhaust pluse a enermax 120mm chimney fan (all of them at about 1500 rpms i have a hard time hearing them from 2 feet away but they move alot of air) and all of my systems are running cooler then when they had stock cooling on them

larva · Nov 4, 2003

IMOG said:
In heatsinks that are designed identically, with no difference except in the materials used - a pure copper heatsink will perform better than an ALCU combo.

The proof is in the pudding. As astutely pointed out by the lostcircuits review, if there is a winner it is the aluminum version. At best the copper one is equal, but there's no way to support the conclusion that it performs better.

I.M.O.G. · Nov 4, 2003

I'm guessing that the better construction of the ALCU version is what makes its performance equal or better - lostciruits mentioned that the hold down in the ALCU seemed to be improved from the CU version they tested.

On a side note... I shouldn't have said this in my last post: "It also shows that the CU version is not a considerable improvement over the ALCU". What I meant was that if the CU version could possibly even be better at all, the review shows that it is not better by any considerable amount.

cyberwiz01 - The design may be identical, but the construction was not. They mention that the CU version had a hold down that was not as secure/strong as the ALCU version. Hold down force can play a considerable part in the heat transfer through the TIM joint.

modenaf1 · Nov 4, 2003

ok getting back on the origional topic of the thread, your temps may not show as great of an improvement with the new heatsink becuase that could be partly limited to the airflow over/through the heatsink, also, if your case temp is within about 5-10 degrees of the cpu temp (the cpu surface temp, not the internal diode), then having a good heatsink should not make that much of a difference. If you have increased airflow throughout the case, maybe have case temps 30-33 C ish then that should make a larger difference between having a good heatsink vs. a bad one. My thinking here is that if you have a better heatsink that disipates air better, dosent make much of a difference if the ambient temp inside the case keeps the heatsink from disipating any heat.

IMOG said:
Aluminum does not dissipate heat better than copper under a constant heat load. This is explained her e.

I agree. For some reason the image that your link conveys in my mind is that aluminum might have greater performance when the constant heat load is less, for example a less overclocked processor, or or lower end one that is not even overclocked at all. Becuase, aluminum has a higher specific heat (see quote below). From what i understood is that if the heat load on the heatsink is less, then the specific heat rating of the heatsink should not matter as much as the actuall heat disipation.

from the General heat transfer Guide on AMDmb.com

Fact 1: Aluminum has a higher specific heat and lower density than Copper. Specific heat is a measure of how densely a material can store thermal energy. If you add thermal energy to a specific mass of material, it will increase in temperature.

The specific heat of aluminum is 903 joules/kg*K at 300K while copper is only 385. The density of aluminum is 2702 kg/m^3 at 300K while copper’s is 8933. The product of specific heat and density determines how much energy may be stored in a given volume. For a given volume of material, copper will store more energy at a given temperature change than aluminum.

False Perception: Since aluminum stores less energy per volume, it must be more efficient at getting rid of heat.

Truth: During steady-state operation, there is no net energy storage in the heat sink or fins/pins; hence, specific heat plays no part in steady-state performance.

Fact 2: Aluminum has lower density than Copper. Volume for volume, aluminum is much lighter than copper.

False Perception: Weight acts as a “sink” for heat. Since copper is more dense, it absorbs heat well from the die. Since aluminum is light, it gets rid of heat more effectively than copper.

Truth: Density has no direct relationship with steady-state heat transfer.

Fact 3: A small volume of aluminum will cool more quickly than an equal volume of copper once the heat source is gone. This is due to the same reason as fact #1, namely there is less energy stored per unit volume is aluminum than copper. This is, however, a transient condition. Heat transfer from a computer is a steady-state condition where the temperature of the heat sink remains relatively constant. The specific heat of a material partially determines how a material responds to transient conditions but has no effect at all on steady-state operation.

False Perception: Since aluminum cools more quickly once a heat source is removed, it must be more efficient at convection.

Truth: The heat source driving energy into the heat sink remains in effect until you turn off your computer. If you have aluminum pins or fins, congratulations, they will cool off more quickly than copper ones after you shutdown your PC.

Partly why i think the the Zalman AlCu has greater performance could also be a factor of the heatsink itself being light meaning less pull and more force on the cpu meaning greater surface contact if it isnt lapped perfectly smooth?

ZL1 · Nov 4, 2003

modenaf1 said:
ok getting back on the origional topic of the thread, your temps may not show as great of an improvement with the new heatsink becuase that could be partly limited to the airflow over/through the heatsink, also, if your case temp is within about 5-10 degrees of the cpu temp (the cpu surface temp, not the internal diode), then having a good heatsink should not make that much of a difference. If you have increased airflow throughout the case, maybe have case temps 30-33 C ish then that should make a larger difference between having a good heatsink vs. a bad one. My thinking here is that if you have a better heatsink that disipates air better, dosent make much of a difference if the ambient temp inside the case keeps the heatsink from disipating any heat.

yes I agree, I was looking at this the wrong way
see with all other things being equal an upgrade should of changed things, but I didnt realize that zalman shows improvement mostly when the airflow is good

D

I.M.O.G. · Nov 4, 2003

Actually Modena, the link explains that specific heat is a null factor in steady state operation - which means under a constant heat load, specific heat would play no part.

All of this boils down to one factor - thermal conductivity. Copper lets the heat move through the heatsink quicker and the heat can get to the air faster.

modenaf1 · Nov 4, 2003

IMOG said:
Actually Modena, the link explains that specific heat is a null factor in steady state operation - which means under a constant heat load, specific heat would play no part.

All of this boils down to one factor - thermal conductivity. Copper lets the heat move through the heatsink quicker and the heat can get to the air faster.

Thanks IMOG.

I dont really take in that real technicle stuff that well

so youll have to forgive me if im wrong again l

ol. So anyways, since copper transports the heat better and faster, but Aluminum gets rid of it faster, wouldnt the optimal configuration be something like the Thermalright ALX 800 or

the Zalman one being discussed in this thread? Be

cause the copper transfers it and the Aluminum gets rid of it? Or would the best configuration be something like having a thin copper base and

structure of a heatsink, and then being able to spray molten aluminum over it in a really fine coat?

and i just scrolled back to the positive life and smilies part so now i feel like thowing some smilies in randomspots of my post

ZL1 · Nov 4, 2003

modenaf1 said:
and i just scrolled back to the positive life and smilies part so now i feel like thowing some smilies in randomspots of my post

when did I use smiles randomly ?? I think I used them accordingly even if one too many times (but I explained why and I dont see anything wrong with that)

D

I.M.O.G. · Nov 5, 2003

A top coat or mixture would just slow things down.

In order for either to be effective, they would have to draw the heat from the copper faster than air could or conduct the heat better than copper does to a larger surface area... Otherwise it would just be better to have copper directly in contact with the air.

modenaf1 · Nov 8, 2003

ZL1 said:
when did I use smiles randomly ?? I think I used them accordingly even if one too many times (but I explained why and I dont see anything wrong with that)

D

ah nah man, its all cool. I was just kidding around, being an ***, that type of stuff.

CHeers!
-f1

Installed Zalman 7000A (AL/CU) on a P4 2.4C, temps pretty much the same :(

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