I am thinking about getting a vf700 for my 6800GT since it runs so hot. I am wondering if all copper is better than a copper/aluminum one. I have yet to decide if I am going to change out the HSF because it may void my warranty.
Copper or Aluminum/Copper?
- Thread starter Compnewbie01
- Start date
Copper can absorb more heat than Al gram-for-gram, but it doesn't transfer the heat nearly as well. So I like the combination of Cu and Al to use the best features of both.
.b.h.
.b.h.
Weight is usually the big issue with copper, but a GPU heatsink shouldn't weigh all that much.
Now as for the CNPS7700 series...AlCu is the only way to go.
Now as for the CNPS7700 series...AlCu is the only way to go.
Actually the 7000AlCu outperforms the 7700AlCu..
It's quieter and gives slightly better cooling performance and it's smaller.
Elcs
Diamond Member
- Apr 27, 2002
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For the VF700, Copper is the way forward.
Considering how well a gfx card + heatsink is supported compared to cpu/heatsink, I doubt theres a major issue with using a VF700Cu compared to an Al-Cu.
My VF700Cu has been on my 9800 pro for months without issue.
Considering how well a gfx card + heatsink is supported compared to cpu/heatsink, I doubt theres a major issue with using a VF700Cu compared to an Al-Cu.
My VF700Cu has been on my 9800 pro for months without issue.
That doesn't even make sense as if it is absorbing the heat it is also transferring
it from the CPU.
The only advantage Al over Cu is that it cools faster once the heat source has been removed.
Not important in a CPU heatsink where we have a steady state operation.
I got a Cu/Al for my 6800 because the reviews I read said at silent fan settings it was better or just as good at maintaining temps as the solid Cu unit. At high speed fan operation the all copper unit will out perform the Cu/Al by only 1 or 2 degrees.
The all copper costs more and as allready stated weighs more. They are both good.
Aluminum does tranfer heat to the air better and copper can hold more heat. The high fan speed is needed to *scrub* air against the copper because it does not radiate or release its heat load as easily as aluminum.
Just to put a finer point on it. To get the very best out of whatever you decide to use, the graphics card processor and CPU chip can also be lapped to true flatness to get the ultimate in surface contact. Doing this is not reccomended and voids all warrenty. But some ppl will venture into this area. The tinyest dot of paste is used at installation.
As many have, I lap all heat sinks. I have not lapped a CPU *yet*, my P4 2.8 is out of warrenty soon. We shall see ;-)
The all copper costs more and as allready stated weighs more. They are both good.
Aluminum does tranfer heat to the air better and copper can hold more heat. The high fan speed is needed to *scrub* air against the copper because it does not radiate or release its heat load as easily as aluminum.
Just to put a finer point on it. To get the very best out of whatever you decide to use, the graphics card processor and CPU chip can also be lapped to true flatness to get the ultimate in surface contact. Doing this is not reccomended and voids all warrenty. But some ppl will venture into this area. The tinyest dot of paste is used at installation.
As many have, I lap all heat sinks. I have not lapped a CPU *yet*, my P4 2.8 is out of warrenty soon. We shall see ;-)
Copper, but heaps heavier - think aluminium can -v- chevy camaro. Probably no as bad as that, but if your board etc can handle the extra weight, then copper...
> " Aluminum does tranfer heat to the air better and copper can hold more heat. " <
Common misconception - but we'll leave it at that.
Common misconception - but we'll leave it at that.
JBDan
Platinum Member
- Dec 7, 2004
- 2,333
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Originally posted by: Susquehannock
> " Aluminum does tranfer heat to the air better and copper can hold more heat. " <
Common misconception - but we'll leave it at that.
No misconception...maybe different wording...Al transfers/releases heat "faster/quicker" (hence, better
)to the air than copper does. Cu can "hold in/absorb" more heat than Al being a denser metal, but because of this property Cu is slower to release heat. Simple test any1 can do...touch a Al HS 1 minute after shut down and touch a Cu HS 1 minute after shutdown. The difference is very obvious.Gah.
Metals have two relavant properties:
Thermal CONDUCTIVITY and thermal CAPACITENCE.
The first is how well heat moves THROUGH the metal, and the second is how much heat the metal holds per unit of weight per degree of temperature. (Put another way, how much energy is needed to raise 1 mass unit 1 temperature unit.)
So, at 70C, a copper part has more heat in it than an aluminum part of the same size. Because thereis more heat there, if you turn off the GPU, it will remain hotter longer. Conversely, it will take LONGER for the copper sink to heat up than an Al one. So when you first turn on your part, the Al part will vent more heat - but that's because it'll get up to 70C really fast. The Cu part won't vent heat as quickly, because it'll take longer to get up to 70C. (Either way, the hotter the part, the more heat you vent, since air will pick u more heat from a hot part than a coldone.) Trying to argue that Al removes heat better because it gets cooler faster is stupid - there was just less heat in the aluminum.
Either way, your sink will eventually get up to the equilibrium temperature. At that point, three things matter:
- SURFACE AREA of the sink: The bigger the surface area, the more air is in contact with it, pulling heat away.
- AIR FLOW through the sink: More air going through, the cooler the air is, and the more heat you pull out. (Heat transfers better the larger the difference between two materials.)
- THERMAL CONDUCTIVITY of the sink: You want the temperature of the sin next to the air to be as close to the temperature of the part you're trying to cool. If a part has HIGH thermal conductivity, heat moves through the part easily, and as air cools the part of the sink away from your part, heat from the part will quickly move thorugh the sink to keep the temperature next to the air high. If your thermal conductivity is low, then your air will cool the sink, but the heat from the part won't be able to move through the sink as quickly, so the air isn't able to pull as much heat of fthe sink.
For example, let's say the part is 70C. With high thermal conductivity, the edge of the heat sink is also close to 70C, and your air is 25C, giving you a full 45C difference between the sink and the air. With low thermal conductivity, the temp on the edge of the heat sink may only be 60C, meaning lower temp difference, and the air moving less yeaet away (which will ultimately push the part's equilibrium heat point above 70C).
SO, which is better, Cu or Al?
Copper is 4.01 W/cm/K, Al is 2.37. Copper is significantly better. (Of course, an AL fan with more surface area and more air flow might still be better than a Cu fan with less.)
Metals have two relavant properties:
Thermal CONDUCTIVITY and thermal CAPACITENCE.
The first is how well heat moves THROUGH the metal, and the second is how much heat the metal holds per unit of weight per degree of temperature. (Put another way, how much energy is needed to raise 1 mass unit 1 temperature unit.)
So, at 70C, a copper part has more heat in it than an aluminum part of the same size. Because thereis more heat there, if you turn off the GPU, it will remain hotter longer. Conversely, it will take LONGER for the copper sink to heat up than an Al one. So when you first turn on your part, the Al part will vent more heat - but that's because it'll get up to 70C really fast. The Cu part won't vent heat as quickly, because it'll take longer to get up to 70C. (Either way, the hotter the part, the more heat you vent, since air will pick u more heat from a hot part than a coldone.) Trying to argue that Al removes heat better because it gets cooler faster is stupid - there was just less heat in the aluminum.
Either way, your sink will eventually get up to the equilibrium temperature. At that point, three things matter:
- SURFACE AREA of the sink: The bigger the surface area, the more air is in contact with it, pulling heat away.
- AIR FLOW through the sink: More air going through, the cooler the air is, and the more heat you pull out. (Heat transfers better the larger the difference between two materials.)
- THERMAL CONDUCTIVITY of the sink: You want the temperature of the sin next to the air to be as close to the temperature of the part you're trying to cool. If a part has HIGH thermal conductivity, heat moves through the part easily, and as air cools the part of the sink away from your part, heat from the part will quickly move thorugh the sink to keep the temperature next to the air high. If your thermal conductivity is low, then your air will cool the sink, but the heat from the part won't be able to move through the sink as quickly, so the air isn't able to pull as much heat of fthe sink.
For example, let's say the part is 70C. With high thermal conductivity, the edge of the heat sink is also close to 70C, and your air is 25C, giving you a full 45C difference between the sink and the air. With low thermal conductivity, the temp on the edge of the heat sink may only be 60C, meaning lower temp difference, and the air moving less yeaet away (which will ultimately push the part's equilibrium heat point above 70C).
SO, which is better, Cu or Al?
Copper is 4.01 W/cm/K, Al is 2.37. Copper is significantly better. (Of course, an AL fan with more surface area and more air flow might still be better than a Cu fan with less.)
Wow, excellent post raehl I'm in the same boat as everyone else it seems -- what heatsink to get
I'm in the same boat as everyone else it seems -- what heatsink to get 
JEDIYoda
Lifer
- Jul 13, 2005
- 33,986
- 3,321
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Originally posted by: Susquehannock
> " Aluminum does tranfer heat to the air better and copper can hold more heat. " <
Common misconception - but we'll leave it at that.
Obviously you didn`t read and totally comprehen what Galvanzed stated....
In the context that Galvanized used he was 100% correct.
He even stated why..also very accurately....
Personally when deraling with copper its not a slam dunk that copper will out perform ALuminum......but depending on the fans you use or are stuck with due to facotry install of fan on CPU....you will get what Galvanized stated!!
As for general information not even developing or commenting on what Galvanized posted that was a nice article raehl!!
Raehl, you are apparently a metalergical engineer or up-coming one.
Now, what of the different aluminum alloys. Many have a high concentration of copper and this will be a factor in HS manufacturing. I'm speaking of the higher-end aluminum HSs not
the cheaper extruded ones.
For our purposes moving the heat to contact with the air is of prime importance. More suface area with less mass is a big plus. In a water cooled PC copper would be better for any number of reasons, reaction with the coolent the major one.
Galvanized
Now, what of the different aluminum alloys. Many have a high concentration of copper and this will be a factor in HS manufacturing. I'm speaking of the higher-end aluminum HSs not
the cheaper extruded ones.
For our purposes moving the heat to contact with the air is of prime importance. More suface area with less mass is a big plus. In a water cooled PC copper would be better for any number of reasons, reaction with the coolent the major one.
Galvanized
HardWarrior
Diamond Member
- Jan 26, 2004
- 4,400
- 23
- 81
It depends on the design of the HS. Cooper as a contact surface works well for thermal transfer and holding capacity. Aluminum works well as a heat dissipator because it's less dense. So, if the HS has the right metal in the right place it can work very well. Oh, and replacing a HS on a video card does void your warranty, but as a fallback just keep track of every piece of the stock HS and be prepared to reattach it if need be.
You can look at copper/aluminum cooling potential several ways. What cools better.....a one pound copper heatsink, or a one pound aluminum heatsink, the fins on each being the same diameter?
Well the aluminum heatsink will cool down much quicker. Why...because of the much greater surface area.
Well the aluminum heatsink will cool down much quicker. Why...because of the much greater surface area.
BonzaiDuck
Lifer
- Jun 30, 2004
- 16,443
- 1,938
- 126
Copper for the base and processor-cap interface -- for its direct contact with the cap as a source of heat-transfer. Copper can absorb a lot of heat with less changes in temperature. Aluminum fins -- for low-weight/high-surface-area, better conductivity for air as transfer medium.
That of course returns you to an Alpha 8942/8952. Thick copper base with aluminum pin fins, which give more surface area than a standard fin......
Still one of the best heatsinks out there, maybe the best excluding heat pipes. Plus.....it fits better than most/all of the Zalman round clones. And you can operate in the suck mode, unlike the Zalmans.
Still one of the best heatsinks out there, maybe the best excluding heat pipes. Plus.....it fits better than most/all of the Zalman round clones. And you can operate in the suck mode, unlike the Zalmans.
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