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- - what heatsink (https://www.madshrimps.be/vbulletin/f10/what-heatsink-4018/)

soon I'll put my Linux machine back together. I'm wondering what heatsink I should use. I've used my SLK800 before, with a silent 7V fan the CPU got pretty hot: stock speed +40 idle, stressed: dunno. stressed, a temp probe between some fins of the SLK reported 44°

I'm using a Koolance case. the PSU is 300W and has a silent fan at 5v (pretty close to unhearable).

I've got two heatsinks available: my stock 2500+ heatsink with copper base and a V7+ heatsink. both will be used with 60-80mm fan adapter. I'll put a few casefans in the machine, but they'll only push very little airflow. same goes for the CPU fan, it used to be 7V but now I want to give it only 5Volt

so, what HS performs best with little airflow? I think the 2500+ heatsink, because copper heatsinks need a LOT of airflow to work properly... copper doesn't give away like aluminium does

i would think de aluminium one , but test it , its not too much work is it ?

actually it is :/

I don't want to test the heatsinks, compare them and take everything apart every time

then take the risk , take the alu :)

I shouldn't doubt about it. The stock amd heatsink has a copper base and alu fins so it should perform better with a less performant fan.

The stock HS will prolly work better, because there is more distance between the fins so there's no need for high CFM to get the air at the base.

true go with the heat dissapation of the alu.

copper takes absorbes the heat much better but alu can give away the heat better
so take te alu one, and same reason like HardFreak

Quote:

Originally posted by Da_BoKa
copper takes absorbes the heat much better but alu can give away the heat better
so take te alu one, and same reason like HardFreak

Actually, according to my lessons physics, that isn't true.
I think the copper will perform better because it has more fins. And I think it will even perform better with the fan-adapter. Just my 2 cents.

Quote:

Originally posted by Laagvliegerke

Actually, according to my lessons physics, that isn't true.
I think the copper will perform better because it has more fins. And I think it will even perform better with the fan-adapter. Just my 2 cents.

well, that's what most people say. I'm going with the alu, copper needs a lot of airflow to cool well

Quote:

yes Cu wil perform better with more airflow

buth the fins from the alu HS have more space between them and will perform better with less flow

but my gues is the difference will be a couple of degrees

Cu will be better, the ALU will only start performing good with a high CFM fan.

I would take the Cu,

I thought that CU could take up more heat...at least it heats up faster...

so, nobody knows? :D

I'll check both

Quote:

Originally posted by TeuS
so, nobody knows? :D

Quote:

Cu will be better, the ALU will only start performing good with a high CFM fan.

Quote:

Originally posted by jmke
Cu will be better, the ALU will only start performing good with a high CFM fan.

me and some other people think the opposite. I'll test it today!

you should go for the alu one

Quote:

Originally posted by TeuS
me and some other people think the opposite. I'll test it today!

http://www.systemcooling.com/modules...ticle&sid=1288

SUMMARY: Excellent choice for aggressive air-cooling, but at very high noise levels.

an ALU heatsink can only keep up with a CU one if high CFM fans are used, when low CFM are used the CU will outperform because it can absorb more heat, thereby cooling the CPU more, while the ALU's heat absorbtion will be less, leaving the CPU running warmer.

we'll see

don't forget we're talking about totally different heatsinks :)

no, I forgot about that.

my 2nd machine is home again, I'll start testing.... er....

how about now :D

ok, here's the setup
Koolance Case, 350W Enermax PSU, dual fans at low speed

ECS K7S5A, 2000+ Tbred A, a stock 2500+ heatsink (alu-cu), a v7+ heatsink and the 2500+ 60mm fan. I'll also do some testing with a 60-80mm fan adapter and a silent 80mm sleeve bearing fan

alu/cu, 60mm fan, 12v: CPU 43°, case 32°, ambient 25.5°

and the copper one? :)

heheheheh. I have my own way to test heatsinks

same setup, fan on 7volt: CPU 51, case 31~32

fan at 5v: CPU 62, case 31

if my 60-80mm fan adapter gets here by the weekend I'll wait to test with a 80mm fan, if not I'll test the V7+

v7+ heatsink: CPU 49, case 33

V7+, fan at 7v: 58°/31°

Quote:

Originally posted by 8-ball
When will people learn that HSF manufacturers only use aluminium because it is:

cheaper
lighter
cheaper
easier to manufacturer
cheaper

and did I mention cheaper.

I will concede that aluminium DOES radiate thermal energy better than copper. However, raidation is simply not a significant mode of heat dissipation unless you are cooling something in a vacuum. It also needs to be significantly hotter than the surroundings to get a reasonable amount of heat dissipation.

As for convection.

Convective heat transfer, the process by which thermal energy is transferred from a solid into a moving body of fluid, such as water in your water block, or air flowing through a rad, is INDEPENDENT of the material of which the rad/block is manufactured.

The only bearing the material has on the heat transfer is getting the thermal energy to the surface. Once it is at the surface, it may as well be glass for all I care. The only thing which determines how well the thermal energy is dissipated in to the air flow, is the physical properties of the liquid/gas, the flow regime, and the geometry of the transferring surface.

8-ball

Quote:

Originally posted by 8-ball
Aluminium IS a better radiator, in that its radiating properties are closer to that of a black body than copper.

However, as I said, radiation simply doesn't figure significantly enough for using aluminium to perform better than copper due to the performance hit associated with the conduction of thermal energy to the dissipating surface.

Just about the only scenario where aluminium's better radiating (and let me point out, that it isn't that much better) properties justify it's use are in space, where ALL thermal energy must be dissipated by radiation due to the vacuum.

As long as there is some medium to carry the heat away by convective heat transfer, then radiation properties are pretty irrelevent.

8-ball

Quote:

Originally posted by 8-ball
As i understand it, the myth that aluminium is a better radiator, (and a common myth) is down to the radiative properties of the materials. It is true that aluminium is a better radiator, but radiation doesn't playa big enough role for this fact to outweigh it's much poorer conductivity.

As I alos said, and you correctly backed up, cost is the predominant factor in using aluminium over copper for thermal management applications, and maybe weight.

8-ball

http://www.xtremesystems.org/forums/...threadid=30286

Quote:

Originally posted by TeuS
V7+, fan at 7v: 58°/31°

ineens 7°C warmer als voor den edit? :p

Quote:

Originally posted by jmke

ineens 7°C warmer als voor den edit? :p

had HDD power off aangeleged (HDD is luid), waardoor prime stopte (??) en de CPU weer ging idlen (wat ik niet op tijd merkte)

5v fan: CPU 72°, case 30°

the results... I hope they make sense, some things don't seem really logical :shrug:

I'll check everything tomorrow, re-check temps if needed.

results are not 100% perfect (ambient temp, cool paste burn-in) but that was not the goal

V7+ sucks, is what I'm thinking :)

Quote:

Originally posted by jmke
V7+ sucks, is what I'm thinking :)

yep, me too. if you've got a better copper (60mm) heatsink, feel free to ship it with the TEC. perhaps we'll get different results

I conclude from this test there's no real difference between the Alu/Cu and full Cu heatsinks when it comes down to CFM, the temperature rises equally as the CFM drops

Quote:

Copper heatsinks are no good for passive cooling, that's what most people don't know. It's because copper can conduct the heat faster than for example aluminium, but it also keeps the heat longer inside than the just named aluminium. That's the problem with copper and passive cooling. Copper needs to be ventilated to have a better cooling effect than aluminium. Aluminium is far superior to copper when it comes to passive cooling, as the Alu can pass on the heat to the surrounding air much quicker than copper can. The absolute best solution for passive cooling would be a heatsink with copper base and large aluminium body (fins).

http://www.xtremesystems.org/forums/...threadid=30929

so people don't really know what they are talking about, since everyone is saying something different.

That's where the high school (or better, university) physics teachers come into play (they do have a use afterall)

Quote:

Originally posted by Liquid3D
Celemine1Gig to the forum. I truly appreciate someone with a working knowledge of metalurgical/thermodynamics. The assessment was on the money in his/her replies. For a passive radiator copper isn't as effective as aluminum, and this where many of the "myth's" of aluminum's conductivity compared to copper become pertinent. For the longest time I simply thought mobo makers whom used passive NB/heatsinks, did so primarily for cost, and in many cases I'm sure they do.

I'll try to get some books about thermodynamics thought :)

Quote:

Originally posted by Da_BoKa
copper takes absorbes the heat much better but alu can give away the heat better
so take te alu one, and same reason like HardFreak