What material is the bottom plate screwed on a stock t-bred heat sink?

[Macro2]

Appears to be steel/iron thats plated...maybe zinc plated?
What is the heat transfer coefficent of steel vs aluminum and copper? (all you material/physics majors) Just thinking they use this plate rather than aluminum or copper for some reason besides cheap...if that...

 

[MichaelD]

They use it b/c of cost...OEM HS are very cheap to produce. The OEM HS does a fine job as long as you're not OCing.


AFA the rest of your questions:

Copper is the best conductor of heat, AFA heatsink materials go. But, aluminum dissipates heat faster. An all-copper HS needs a mighty fan to keep it cool, as it conducts heat far better/faster than an all aluminum HS.

Combining the two materials gives you the best of both worlds, ala an Alpha8045 or Thermalright AX-7. These HSs have a copper bottom plate welded to an aluminum HS. The copper plate conducts the heat away from the CPU core quickly, while the aluminum body dissipates the heat quickly.

Hope this helps.

 

[RSMemphis]

Sorry MichaelD, but I have to disagree here.

The reason why copper is not used for an entrire heatsink is not because aluminum passes heat better into air (it does it as well as copper), but:

1) Al is lighter
2) Al is cheaper
3) Al has an aluminum oxide layer that protects it from corrosion, copper just corrodes more and more.

Al thermal conductivity (scroll to bottom): 235

Cu thermal conductivity (scroll to bottom): 400

That's almost twice as good!!!
The thing is, you only need the copper to get the heat away from the CPU, then the aluminum does a decent enough job to get it the rest of the way.

 

[MichaelD]

Uh, isn't that what I said? Maybe I wasn't clear...

Copper sucks heat away faster than aluminum, BUT
Aluminum cools faster than copper does.

That is why you have HS's with a copper bottom plate and an aluminum body. I know the diff, but maybe I worded it wrong?

ps
The SLK-800 is an All-Copper HS.

 

[Actaeon]

Originally posted by: MichaelD
They use it b/c of cost...OEM HS are very cheap to produce. The OEM HS does a fine job as long as you're not OCing.


AFA the rest of your questions:

Copper is the best conductor of heat, AFA heatsink materials go. But, aluminum dissipates heat faster. An all-copper HS needs a mighty fan to keep it cool, as it conducts heat far better/faster than an all aluminum HS.

Combining the two materials gives you the best of both worlds, ala an Alpha8045 or Thermalright AX-7. These HSs have a copper bottom plate welded to an aluminum HS. The copper plate conducts the heat away from the CPU core quickly, while the aluminum body dissipates the heat quickly.

Hope this helps.

A correction, Silver is the best element conductor of heat. While Diamond is the best natural resource conductor of heat. Of course, both are two expensive to mass produce. Copper is available in much larger quantitys, and is much cheaper. As is aluminum.

I currently own an Alpha 8045, great HSF.

 

[RSMemphis]

Originally posted by: MichaelD
Uh, isn't that what I said? Maybe I wasn't clear...
Copper sucks heat away faster than aluminum, BUT
Aluminum cools faster than copper does.

The first part is right, the second part is the one I disagree with you about. Aluminum does NOT cool faster than copper, it's CHEAPER than copper.

And as you said, the SLK-800 is all copper, and it is one of the best heatsinks out there right now.

 

[Macro2]

So where are zinc and iron?

I think most white silicone pastes for heatsinks contain zinc oxide powder. (not unlike that stuff you put on your nose to block the sun).
I would expect then that silver is better than zinc (artic silver).

OTOH, how much money does AMD save by using a (zinc or ? plated) plate on the bottom of aluminum opposed to an all aluminum HSF with a milled slot? I'd venture to say the extra plate costs more that just milling a slot since you have the operation of stampmg a plate, plating it, drilling it. tapping the aluminum heatsink and then screwing it on.
This points to the steel plate being a better drawer of heat than straight aluminum. Less chance of warping too.

OTOH, why use steel instead of Copper? The price difference would be nil really...especially since copper is easier to stamp and machine and doesn't have to be plated.

 

[MichaelD]

Originally posted by: RSMemphis

Originally posted by: MichaelD
Uh, isn't that what I said? Maybe I wasn't clear...
Copper sucks heat away faster than aluminum, BUT
Aluminum cools faster than copper does.

The first part is right, the second part is the one I disagree with you about. Aluminum does NOT cool faster than copper, it's CHEAPER than copper.

And as you said, the SLK-800 is all copper, and it is one of the best heatsinks out there right now.

Oh, OK...I'm not a metallurgist or anything...I just buy the stuff and it works....I go away now.

 

[Macro2]

I pulled some specific heat (Specific heat is the quantity of heat required to raise the temperature of one gram of a substance by one degree Celsius at constant pressure) values off the net. Interesting that zinc and copper are nearly identical at .094 and .093. Iron is not too different than copper or zinc at .108. Aluminum is high at .215 and silver is low at .056.
Even lower than silver's specific heat are platinum .032 and .031 gold.

Link

So if lower specific heat metals like copper, zinc, silver etc are better pressing on the die (drawing the heat away?) vs a metal like Aluminum that would dissapate heat better like Aluminum it would make sense that a copper insert Alumunum heatsink would be good. Much better than a all aluminum heatsink. BUT not much better if at all than a heatsink like the AMD stock heatsink that uses a steel plate (maybe zinc plated)

On the other hand....Gold .031 has an even lower specific heat than silver. So where are the gold plated-copper insert heatsinks?

 

[Macro2]

RE:"A correction, Silver is the best element conductor of heat."

Seems like Gold, lead and platinum are better conductors of heat than silver. They have significantly lower specific heats than silver. Aluminum on the other hand is a relatively poor conductor of heat and consequently holds it's heat longer than other metals.

 

[Macro2]

According to this guy, Aluminum fins are no better than copper ...in real world use.
http://www.amdmb.com/article-display.php?ArticleID=105&PageID=4

 

[MichaelD]

I'll just add this: the AX-7 is the first copper-plate-bottomed CPU HS I've ever had, and it's really great. The copper plate makes a noticeable difference in CPU temps

 

[Macro2]

I think that other than solid gold, a thin finned solid copper heatsink is about the best you can get.

 

[Macro2]

Also the stock t-bred heatsink is about as good as a copper insert HSF of the same size AND better than a solid aluminum heatsink by a lot.

Mac

 

[mechBgon]

For the record, I believe the bolt-on plate is nickel-plated copper. Next retail AMD heatsink I get that has one, I'll attack a corner with a hand file and confirm that.

 

[Macro2]

Just stick a magnet on it.

 

[Insane3D]

Originally posted by: RSMemphis
Sorry MichaelD, but I have to disagree here.

The reason why copper is not used for an entrire heatsink is not because aluminum passes heat better into air (it does it as well as copper), but:

1) Al is lighter
2) Al is cheaper
3) Al has an aluminum oxide layer that protects it from corrosion, copper just corrodes more and more.

Al thermal conductivity (scroll to bottom): 235

Cu thermal conductivity (scroll to bottom): 400

That's almost twice as good!!!
The thing is, you only need the copper to get the heat away from the CPU, then the aluminum does a decent enough job to get it the rest of the way.

Actually my friend, MichaelD is right. Copper transfers heat better than Aluminum, however, it can't "shed" heat as well as aluminum can. This is a well know fact of the behavior of these two metals. A pure copper HSF will absorb the heat faster, but the copper will tend to hold the heat more, and requires a higher CFM fan to help it dissapate the heat.

 

[Macro2]

Well I just stuck a magnet on it and it's NOT magnetic. Could be plated copper or a non magnetic 300 series stainless steel.

Interesting. Appears there is more to the stock HSF than I thought.

 

[Macro2]

RE:"This is a well know fact of the behavior of these two metals. A pure copper HSF will absorb the heat faster, but the copper will tend to hold the heat more, and requires a higher CFM fan to help it dissapate the heat."

Except that thin finned copper supposedly more than compensates for that.

LINK

 

[Insane3D]

Originally posted by: Macro2
RE:"This is a well know fact of the behavior of these two metals. A pure copper HSF will absorb the heat faster, but the copper will tend to hold the heat more, and requires a higher CFM fan to help it dissapate the heat."

Except that thin finned copper supposedly more than compensates for that.

LINK

Fairly true, but it means that have to do something different to all copper HSF's to compensate for the phenomena...

 

[Macro2]

I think we agree that copper in contact with the die is good. I'm wondering why AMD didn't do this. Corrosion maybe? OTOH, I've beat this subject to death now. Learned a lot though.

Mac

 

[Insane3D]

Well, I guess it depends. I rarely buy retail CPU's but I recently bought a 2200+ retail for a customer build, and it came with the copper bottomed Taisol. The only difference was the sticker on the fan said AMD instead of Taisol, but it was clearly the Taisol.

 

[Macro2]

Interesting. I recently got a retail 2400+ and it came with a Aluminum HSF with a plate on it. Silver colored. Either Stainless steel or plated. The clip said Taisol on it. The clip was a single latch opposed to the triple on the copper bottomed Taisol I used.
So apparently Taisol is making clips or probably AMDs fans.

 

[Insane3D]

Yeah...it seems to be a crap shoot about which HSF you will get with a retail CPU. My guess is it depends on who gives them a deal that quarter buying HSF in large numbers. They seem to mainly use Coolermaster and Taisol..