Weird experience with copper heatsink

[bbtkd]

We recently built a system with the AMD Athlon XP 3200+. At first we used a $15 aluminum heatsink with a 2700 RPM 80mmx80mm case size fan. At no overclock it ran at 35C (95F). We got a copper heatsink (with smaller 5800 rpm 40mmx40mm thin fan) because we thought it should run cooler when overclocking. So - we installed the copper heatsink, and at no overclock it ran at 65C (149F). Thinking we did something wrong (not enough compound or something) we went back and forth several times but got the same results. Any idea why the copper would register so much higher? Is this due to the fan? Should we get a stepdown adapter (80->40) and a high rpm 80x80mm fan? Thanks!

 

[Crashman]

You'd better get out your ruler and measure that thing, it's not 40x40mm. It might be 60mm.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[folken]

There are 40mm fans out there, if that is all you have on there though I'd say that was your heat problem
80mm fan to 40mm fan and temp doubled, put that 80mm fan on the copper heatsink and you will be set, lol.

<A HREF="http://www.folken.net/myrig.htm" target="_new">My precious...</A>

 

[bigbang]

i had the same problem with a copper heatsink but with a 60mmx60mm fan.
http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&p=627871#627871

this gave me the answer, your heatsink/fan basically is not big enough to lose all the heat it quickly gets from the cpu.

 

[bbtkd]

Thanks for all the input! I did not measure the fans - so the CPU fan may be 60mm. Anyway - we'll look into getting a better setup. I wonder why they even bother selling something like that (we got it "free" with the CPU)...


Tom

 

[bigbang]

copper heatsinks are not that bad, for example zalman cnps7700 is quite big that its copper model gives better performance than its aluminium and aluminium/copper model.
in my opinion, if heatsink is big, it better be copper/aluminium and if its small , it better be aluminium

 

[jammydodger]

Copper is a better conductor of heat than aluminium. It is normally only used on top end coolers as it is more expensive than aluminium.

 

[bigbang]

just because its expensive it doesnt mean its good....

 

[georgebeee]

vantec's website says copper picks up heat better, but aluminum gives it off better. the copper/aluminum in the best bet. also the weight of the copper is an issue

 

[jammydodger]

No the fact that it is a better conductor of heat means its better(4.01 W/cmK compared to 2.37 W/cmK
for aluminium). However it does a specific heat capacity of 0.38J/gK which is much smaller than aluminium at 0.9J/gK. Meaning aluminium can store more heat but copper can move it faster.

 

[georgebeee]

I got an amd 2000+ on a ga-7va(no oc with the via chipset)
with the stock cooling it was running 60C, under load up to 65C. so I purchased a vantec "copper x" model cck-6040h and some arctic silver 5 to go with. with the vantec my temps went up to 65C, under load 73C. oh my!!!

so I took the fan off the vantec, put it on my STOCK aluminum heat sink with some arctic silver and my temps dropped to 33C, under load 40C

copper works better as a heat sink material? you sure about that? my heat sinks are the exact same size, or the fans wouldn't have switched as easily as they did.

 

[jammydodger]

Copper is a better heatsink material as long as you can move the heat away from it quick enough. Other wise it reaches its specific heat capacity too quickly and cant absorb much more heat. Thats why most water and heatpipe coolers are copper.

 

[georgebeee]

the vantec I had used a 6800rpm fan, and had as5 thermal grease. I used the same fan, the same thermal grease, in the same case with the same cooling and I'm getting about 35C cooler than I was with the copper. my system temps are almost always well under 30C--between 25 and 26 currently.

I believe copper is a sturdier metal then aluminum, also weighs quite a bit more. but I don't seem to have any heat problem in my case, at all. and my not OC'd 2000+ prolly isn't the hottest cpu on the market, do you spose? and the copper heatsink seemed to have problems keeping up with it.

guess until I see different I'm into aluminum. and I don't see any reason to shell out $35-50 for crap some company tries to tell me I need. I see a lot of that in today's PC market to tell you the truth

 

[georgebeee]

you think the 33-40C I'm getting from my stock heat sink is a problem? the vantec heat sink had the connector with the 3 tabs on each side and as this is the first time I've ever attached a new heat sink to a cpu I tried at least 6 times(with temps like that I also assumed it was me doing some thing wrong). so, no, there was no contact problem

 

[Untruest]

Sorry to have brought this back alive but, something to note, is that copper may have a lower specific heat capacity than aluminum, but if it were at least 2.3 times heavier than the aluminum heatsink ( given same size to be fair) it would be more effective at reduce the heat.

I read somewhere in this thread that somebody noticed a difference in weight from the two and that copper was heavier. Well maybe this is why copper is a better selection, It's because it's heavier.

This is true in:
Heat gained = mass * specific heat * delta temperature

Anyone denying or agreeing with this fact?

 

[Untruest]

Wusy, please expand on your "YEP YEP". I don't know where you stand.

It's basicaly my theory, and it sounds like it makes sense but maybe 2.3 isn't typical enough. Maybe it's too heavy.

I don't know but i could sure use someone elses insight.