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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Desktops > Is it liquid cooling? Or is it a heat pipe?

Is it liquid cooling? Or is it a heat pipe?
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The Placid Casual
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Jun 9, 2004, 12:14 PM
 
I can see no pump or radiator from the pics I have seen of the new 2.5ghz G5... looks like it uses a heat pipe to me, and not genuine liquid cooling.

That means, no silent operation as fans will still be in there, and no 'new technology' as heat pipes first appeared on the 1.4 Ghz Powermacs last year...

Has the idea that there is liquid in the cooling system just been jumped upon by the marketing guys?

Does it make a difference to buyers?
     
Dyeus
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Jun 9, 2004, 12:24 PM
 
Aslong as there is liquid involved to cool down it is legaly called "liquid cooling" heck you can throw a glass of water on your present system to say that you have "liquid cooled" your maching

Now that was real dumb of me
     
Love Calm Quiet
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Jun 9, 2004, 01:07 PM
 
I don't know where they got the image, but http://www.macminute.com/ depicts the cooling as using a radiator.
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The Placid Casual  (op)
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Jun 9, 2004, 01:25 PM
 
I am looking at the same diagram, and can see no pump...

Both systems (pheatpipe/watercooling) oviously use a heat spreader on top of the CPU, that is then plumbed to a radiator and the rest of the system.

A true water cooled system to me, always has active pump(s) to circulate the water, rather than passive cooling as in Apples current set up which relies on fans and passive cooling.

Apples IMHO is a heatpipe design.
     
The Ancient One
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Jun 9, 2004, 02:04 PM
 
Originally posted by The Placid Casual:
I am looking at the same diagram, and can see no pump...

Both systems (pheatpipe/watercooling) oviously use a heat spreader on top of the CPU, that is then plumbed to a radiator and the rest of the system.

A true water cooled system to me, always has active pump(s) to circulate the water, rather than passive cooling as in Apples current set up which relies on fans and passive cooling.

Apples IMHO is a heatpipe design.
And you WANT pumps? Who cares, as long as it works.
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Jordan
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Jun 9, 2004, 02:13 PM
 
Surely you don't need a pump for liquid cooling. Thermal dynamics will take care of the circulation. Lots of devices use that type of "liquid cooling"
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Jun 9, 2004, 02:35 PM
 
I spilt a cup of water on my desk once, it hit my PowerBook before I could scoop it up and put it down some place dry...

I had liquid cooling way before the G5s!
Take that Apple.
     
Mediaman_12
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Jun 9, 2004, 04:34 PM
 
Liquid heat pipe configs like this are nothing new anyway, I don't know why Apple has decided to hype it up. I first saw one on a Sega Dreamcast console, and there are loads of various PC's you can buy with them like this Hush PC (a cool 'the case is the heatsink' design) and this Shuttle case is the same
     
H * £ £
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Jun 9, 2004, 05:33 PM
 
Why is the diagram showing no heat being produced by the lower of the two CPUs?
     
bradoesch
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Jun 9, 2004, 07:38 PM
 
Originally posted by H * £ £:
Why is the diagram showing no heat being produced by the lower of the two CPUs?
I'm guessing the water is moving in a counter-clockwise diretion in this picture:

     
Eug Wanker
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Jun 9, 2004, 11:49 PM
 
     
klinux
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Jun 10, 2004, 12:45 AM
 
Originally posted by Dyeus:
Aslong as there is liquid involved to cool down it is legaly called "liquid cooling" heck you can throw a glass of water on your present system to say that you have "liquid cooled" your maching

Now that was real dumb of me
If the system is clean room level clean and you threw distilled water on it, it should work fine!

In any case, calling it liquid cooled is slightly exaggerated since in computer world liquid cool generally denotes active cooling i.e. blocks, pump, tubing, etc.

It's just a heatpipe.
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Aykew
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Jun 10, 2004, 01:17 AM
 
From Apple's site:

Mac OS X dynamically adjusts the flow of the fluid and the speed of the fans based on temperature.

At first I thought this might just be slick marketing speak (of course the flow in a heat pipe would be determined by temperature), but if the operating system itself has control of the flow of the fluid, then there must be a pump in there somewhere. Either that or the marketing folks aren't very clear on (or don't care about) the technical nuances of the semantics involved here. (Entirely possible.) Still, since we haven't had any hands-on time with the machine, I think we have to assume that there is a pump of some sort until we can verify otherwise.
     
dar2
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Jun 10, 2004, 01:51 AM
 
If it uses a liquid to effect the cooling, then it's "liquid cooling". Pumps be damned!
     
Elderloc
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Jun 10, 2004, 01:53 AM
 
There is a company that made a dead silent electronic water cooling system that uses Ions to pump the water in a closed loop. this looks like it is an application of it. i know Apple was one of the companys rumored to be looking at it. There was a demo of it on the Screen Savers a few months ago.

Also you can water cool with out a pump it's a convection system as water just like aire will flow when the temps are un even. They are not as effective as pumped systems. I think this is going to become more common over the next year as system reach high temps..
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macaddict0001
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Jun 10, 2004, 02:53 AM
 
Originally posted by Aykew:
From Apple's site:

Mac OS X dynamically adjusts the flow of the fluid and the speed of the fans based on temperature.

At first I thought this might just be slick marketing speak (of course the flow in a heat pipe would be determined by temperature), but if the operating system itself has control of the flow of the fluid, then there must be a pump in there somewhere. Either that or the marketing folks aren't very clear on (or don't care about) the technical nuances of the semantics involved here. (Entirely possible.) Still, since we haven't had any hands-on time with the machine, I think we have to assume that there is a pump of some sort until we can verify otherwise.
The OS could control it without a pump it just needs to use the processor more.
     
andrewhicks
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Jun 10, 2004, 06:16 AM
 
In the picture above, what are the two circular areas on the pipe. Could they have spinning parts that would actively move the liquid around?
     
Aykew
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Jun 10, 2004, 08:52 AM
 
Originally posted by macaddict0001:
The OS could control it without a pump it just needs to use the processor more.
Nice try, but I'm not too emotionally involved in the topic.

In the picture above, what are the two circular areas on the pipe. Could they have spinning parts that would actively move the liquid around?
Anything's possible, but it seems unlikely. One thing to keep in mind is that the illustration on Apple's page is just that. It's probably not meant to be a photorealistic representation of what the thing actually looks like. The illustration has the processors on the same plane as the fan/cooling unit. That would mean that either the processors were perpendicular to the motherboard or the coolers were perpendicular to the airflow, neither of which makes any sense. (Ok, the processors could be on a daughtercard, but that still doesn't make a lot of sense.)

Oh, one more thing-- if it was just a simple heatpipe, why isn't Apple claiming that Powerbooks, which also use heatpipes, are watercooled?
     
ashiver
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Jun 10, 2004, 09:12 AM
 
Originally posted by The Placid Casual:
I can see no pump or radiator from the pics I have seen of the new 2.5ghz G5... looks like it uses a heat pipe to me, and not genuine liquid cooling.

That means, no silent operation as fans will still be in there, and no 'new technology' as heat pipes first appeared on the 1.4 Ghz Powermacs last year...

Has the idea that there is liquid in the cooling system just been jumped upon by the marketing guys?

Does it make a difference to buyers?
From Apple's website:
"Mac OS X dynamically adjusts the flow of the fluid and the speed of the fans based on temperature."

If it had no pump to radiat the coolant, how would it 'adjust the flow of the fluid?'
     
MikeMo
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Jun 10, 2004, 09:17 AM
 
1) There are reactors in submarines that use convection cooling under certain circumstances. No pumps. There used to be one that ran at 60% power with no pumps whatsoever (very quietly). Thousands of gallons of water moving around. Definitely liquid cooled, with highly pressurized water.

2) A heat pipe is generally considered to be something that works explicitly via the thermodynamic properties of the phase change from liquid to gas and back again (also called the "latent heat of vaporization"). Heat pipes also do not have pumps, but that is not a defining characteristic.

3) The web site explicitly states the OS controls the flow. I do not think that means indirectly, via the heat of the CPU. That would be rather obtuse. However, you do not need a pump to control the flow. There could be a small valve in the system that does the same thing. Seems kind of complicated, though. One can also control the flow in a convection system by controlling the speed of the fan on the radiator.

You may now resume speculating.
     
jjqueenan
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Jun 10, 2004, 09:30 AM
 
"Oh, one more thing-- if it was just a simple heatpipe, why isn't Apple claiming that Powerbooks, which also use heatpipes, are watercooled?"

Arrrggh

No one says it's "water" cooled. It's "liquid" cooled.

Anyway, no pumps or ions etc are needed to cause circulation...

1. Liquid starts off cool at startup.
2. Fan and heatsink (dispersion) cools it further.
3. Meanwhile the CPUs are heating up
4. The bottom one receives the cooler liquid first
5. Since there is more heat at the top, and more heat is coming up the pipe from the bottom CPU, the heated liquid sets up a counter clockwise flow (heat rises or in this case will rotate CCW)
6. As it exits the top CPU and enters the radiator area it gets cooled
7. The cooled liquid enters in again though the left
8. Repeat forever.

Circulation is more an effect than a proactive control. Circulation "happens".

The thing being controlled is the fan. More CPU use = more fan usage = more cooling = greater difference in temperature of liquid in the pipe = more circulation.

It is liquid cooled and there is no reason Apple should claim otherwise. Pumps are extreme for the moment, and in this solution, not necessary. And the picture is fairly accurate AFAIK. And it is new to the Mac, these are not regular "heatpipes". That it was used elsewhere previously is a big "so what". It's simply new to the Mac, not to the industry.

I dread the day the PC penis-size-contest bravado comes to the Mac in the form of "my pump is more noisy and energy consuming than yours is!"....
( Last edited by jjqueenan; Jun 10, 2004 at 10:10 AM. )
     
howl
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Jun 10, 2004, 10:11 AM
 
If they can handle the heat load without pumps the more power to them. Fewer moving parts means it might last longer, I guess we will see.

I am wondering about the differential cooling of the processors. In this design, one processor will always run hotter than the other one. I'm wondering with that might result in differences in performance or longevity. It would be interesting to ask the Apple engineers at the WWDC about it. Maybe the difference is negligible, so it may not be an issue, but I'd like to know more.
     
gorbag
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Jun 10, 2004, 10:18 AM
 
Originally posted by jjqueenan:

I dread the day the PC penis-size-contest bravado comes to the Mac in the form of "my pump is more noisy and energy consuming than yours is!"....
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Jun 10, 2004, 10:38 AM
 
Originally posted by Elderloc:
There is a company that made a dead silent electronic water cooling system that uses Ions to pump the water in a closed loop. this looks like it is an application of it. i know Apple was one of the companys rumored to be looking at it. There was a demo of it on the Screen Savers a few months ago.

Also you can water cool with out a pump it's a convection system as water just like aire will flow when the temps are un even. They are not as effective as pumped systems. I think this is going to become more common over the next year as system reach high temps..
It is being develped by Cooligy www.cooligy.com Very intersting setup but th epump then was huge. Then again if they were about to do something like this say, for Apple then they wouldn't want to show off the super secret pump.

Also, about heat pipes. Would a heat pipe, even with a radiator, be engough to cool those CPU's. I did read yesterday, amongst all the other G5 articles, that the liquid is supposed to be a mixture of distilled water and a fluid very similar to anifreeze. Until the 2.5 actually comes out and we see teh system firsthand we won't know.
     
mangacool
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Jun 10, 2004, 11:06 AM
 
Not all pumps are mechanical. There are magnetic and ion pumps as well which can easily push liquid through tubes that small.

But whoever mentioned that changing the speed of the fan can slow and speed up cooling is probably most correct. That facility is already built into MacOS X and is therefore the simplest way to do it. In consumer engineering and design, remember, simpler is better - it's cheaper and there's less to break. Otherwise cars would have fully electronic turn signals by now.

And to those who keep talking about 'heat pipe' technology and relating it to how heat moves from the 'bottom' processor to the 'top' one: Ever consider that Apple's engineers kept in mind people who mount their PowerMac G5 on its side? I doubt they would design something that relies on gravity and convection for that very reason.
     
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Jun 10, 2004, 11:17 AM
 
Originally posted by MikeMo:
1) There are reactors in submarines that use convection cooling under certain circumstances. No pumps. There used to be one that ran at 60% power with no pumps whatsoever (very quietly). Thousands of gallons of water moving around. Definitely liquid cooled, with highly pressurized water.

Very good remark, I read about it in some Clancy novels.
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jjqueenan
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Jun 10, 2004, 11:40 AM
 
Originally posted by mangacool:
And to those who keep talking about 'heat pipe' technology and relating it to how heat moves from the 'bottom' processor to the 'top' one: Ever consider that Apple's engineers kept in mind people who mount their PowerMac G5 on its side? I doubt they would design something that relies on gravity and convection for that very reason.
This is moot.

First, Apple has never endorsed mounting G5s sideways that I know of. Virginia Tech stood them up. Any company doing otherwise isn't Apple's concern.

(Frankly I find most horizontal solutions, and purveyors therof to be just short of reprehensible).

I would assume that unless there is some kind of dip in the pipes (to give it some gravity) inside the radiator that it would not work properly if laid flat (and even then, which way?) or would advection then be the thing at work? Out of my field here...

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( Last edited by jjqueenan; Jun 10, 2004 at 11:47 AM. )
     
klinux
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Jun 10, 2004, 12:21 PM
 
Uh, none of the above. It's the vapor presure in that's causing the liquid to move. Apple could have made water come in through the top or sideways and the liquid would still move albeit less efficiently.
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Eriamjh
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Jun 10, 2004, 12:27 PM
 
Originally posted by andrewhicks:
In the picture above, what are the two circular areas on the pipe. Could they have spinning parts that would actively move the liquid around?
That's where the cooling areas contact the processors!

More than likely, there are no moving parts. Perhaps, electromagnetic pumping action?

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Spliffdaddy
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Jun 10, 2004, 02:08 PM
 
Heatpipe article scanned from 1968 issue of Scientific American magazine. I've never seen a easier-to-understand explanation of heatpipe operation.

Though less effective, they can work even against the force of gravity. Read and learn, young grasshoppers.

www.hillbillytechnologies.com/heat/heatpipe.htm

PS, the original G5 used heatpipes within the heatsinks. The flatpanel iMac uses a heatpipe to link the CPU to the alloy frame - which acts as the heatsink. I have a Pentium 60 laptop that uses a heatpipe. How old is that?
     
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Jun 10, 2004, 05:03 PM
 
Hasn't anyone thought of the picture as a simplified diagram? Some of you seems to think that the picture is the technical blueprint when it's pretty obvious t's not. Apple are obviously educating the ignorant with a easy to understand schematic. We'll just have to wait for some fearless guy from Japan to disasemble it so we can have a real look the cooling device. I don't expect Apple to document it in detail for us since it's probably sealed closed with Patent Pending-stickers.
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Jun 10, 2004, 05:16 PM
 
     
d0ubled0wn
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Jun 10, 2004, 05:20 PM
 
What does this mean for overclocking? Can liquid cooling allow for high overclocking? Any chance of "blowing a gasket"?
     
Eug Wanker
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Jun 10, 2004, 05:25 PM
 
Originally posted by Spliffdaddy:
PS, the original G5 used heatpipes within the heatsinks.
IIRC there are heatpipes on the back of the original G5 mobo too. BTW, I'm thinking the new G5 uses more than just plain heatpipes however.

Originally posted by d0ubled0wn:
What does this mean for overclocking? Can liquid cooling allow for high overclocking?
Perhaps increased chances. However, to date nobody has been able to figure out how to overclock a G5.
Any chance of "blowing a gasket"?
Well, unlikely, since it's a sealed system, presumably built to withstand the pressures. Plus, the system is built with a ton of sensors. If it went beyond some threshold then the system could just throttle the CPUs or shut down the machine or something.
( Last edited by Eug Wanker; Jun 10, 2004 at 05:38 PM. )
     
H * £ £
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Jun 10, 2004, 08:57 PM
 
Apple has added an animation, but it still incorrectly shows no heat being generated by the lower of the two CPUs!?
See http://www.apple.com/powermac/design.html.
     
sith33
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Jun 10, 2004, 11:06 PM
 
A heatpipe can't be a loop either, can it? Because the "loop" portion is actually inside the center of the heatpipe - if you connected both ends, it wouldn't work, would it?
     
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Jun 10, 2004, 11:47 PM
 
It doesn't make sense.. wouldn't that make the first processor in that series run colder than the second?
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csplb
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Jun 11, 2004, 03:39 AM
 
From apples web Page:

Mind-boggling leaps in processing power require innovative design for dissipating heat.

BTW there have been liquid cooled devices for years that do not have pumps. Heat pipes carry heat through a tube as hot air not as a liquid. Thus the term heat pipes. If the pipes or tubes have liquid in them they are considered liquid cooled. If you don't get this just contact one of NASA's research offices and ask them. They use lots of liquid cooling!

Also the flow of the liquid in the units is controlled by increasing the speed of the fan to increase airflow, thus cooling the liquid faster. Go outside your house and look at the airconditioner if you have one. Its a series of pipes filled with freon and a big fan in the middle to force air over the pipes to cool the fluid. (No pumps) Your refridgerator uses the same pumpless system to freeze & cool your food also. Both are known as being liquid/gas cooled. as the freon gets hot it turns to vapor causing the air flow. One big convection pump.

http://forums.macnn.com/newreply.php...ostid=2025871#
( Last edited by csplb; Jun 11, 2004 at 03:46 AM. )
     
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Jun 11, 2004, 03:47 AM
 
In that case, the liquid cooling is noting new since powerbooks have had the same system for ages, just not nearly as elaborate. Hrmmmm
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Mediaman_12
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Jun 11, 2004, 06:17 AM
 
Originally posted by H * £ £:
Apple has added an animation, but it still incorrectly shows no heat being generated by the lower of the two CPUs!?
See http://www.apple.com/powermac/design.html.
and somehow the liquid gets hotter for some reason just before entering the grill. it's possibly the worst diagram ever.

Also I dont know about yours but my FridgeFrezer has a pump that starts up when you open up the door. The only thig Apple has done that makes this system any different than any other 'Heat Pipe' system is add a OS controlled fan (PC moders usually have manual fan controls on the front of the towers).
     
H * £ £
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Jun 11, 2004, 05:58 PM
 
Originally posted by Mediaman_12:
and somehow the liquid gets hotter for some reason just before entering the grill. it's possibly the worst diagram ever.
Does Apple ever proof view this stuff?
Think they'll ever notice the lame diagram and correct it?
     
Aykew
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Jun 11, 2004, 11:30 PM
 
Ok, we can all stop debating about it now! Looks like it's significantly more complex than a heatpipe.Check out these photos! That big black thing in the middle sure looks like a pump to me.

P.S. - I was right! Neener neener neener! (j/k! )
     
Spliffdaddy
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Jun 11, 2004, 11:34 PM
 
Originally posted by sith33:
A heatpipe can't be a loop either, can it? Because the "loop" portion is actually inside the center of the heatpipe - if you connected both ends, it wouldn't work, would it?
ding ding ding

we have a winner.

My twenty bucks says Apple is using *real* liquid cooling. Hopefully without using a pump. Without a pump, it would require the absolute latest technology - microchannels carved into the CPU waterblocks.


(The first pumpless water loop)

There were no pumpless systems like this until last year. It was quite a breakthrough - akin to the creation of the heatpipe. Regardless of what anybody has told you, there were no pumpless systems on the planet until that one shown in the picture was proven to work. There were systems with no moving parts - yet they still required a pump (with no moving parts).

The fact that Apple mentions the nature of the fluid used in their design gives away the game. It's simply water and an antifreeze/anticorrosive additive that will prevent freezing during shipping or storage of the system - as well as prevent corrosion of the metals. A heatpipe wouldn't use that fluid for the expected temperatures of under 140F. It wouldn't be efficient.


edited: four minutes late. Looks like a pump to me.

*sigh*

Although possibly a peristaltic pump like you see in hospitals. Revolving rollers compressing a neoprene hose (positive displacement?).

I see 2 heatpipes, too.

edit again:

If 2.5GHz was that difficult, then 3.0GHz ain't happening anytime soon.

I know the feeling. The newest P4 cores offer one square inch of surface area that produces 100watts of heat. It's almost to the point where even the best metals don't offer enough thermal transfer capacity to cope with such high loads in such a small area. Like a highway with too few lanes.
( Last edited by Spliffdaddy; Jun 12, 2004 at 12:44 AM. )
     
Avon
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Jun 12, 2004, 12:08 AM
 
Originally posted by csplb:
From apples web Page:

...BTW there have been liquid cooled devices for years that do not have pumps. Heat pipes carry heat through a tube as hot air not as a liquid. Thus the term heat pipes. If the pipes or tubes have liquid in them they are considered liquid cooled. ...
You are wrong.

Heat pipes cary heat from one end of the pipe to the other via VAPOR (not air). Vapor heat transfer is responsible for transferring heat from one end of the pipe to the other, and the wicking effect of the capillary tubes (usually a fine metal mesh) on the inside walls of the tube "pump" the water back to the hot side (evaporator) of the tube. The condenser side of the tube is the cold side.

...(No pumps) Your refridgerator uses the same pumpless system to freeze & cool your food also. Both are known as being liquid/gas cooled. as the freon gets hot it turns to vapor causing the air flow. One big convection pump. ...
[/B]

Eh, Are you kidding me? An air conditioner has a powerful pump to compress a refrigerant gas. The pump bring the gas to high pressure then it flows past a throttling valve which lowers the pressure (cools the gas) and flows past the evaporator or heat exchanger. Then back to a condenser (another heat exchanger) then back to the Pump. The fans you are talking about are attached to the condenser. AC units use an large amount of power because of the pump. You should go outside and look at the pump inside your central air.
     
Macrat
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Jun 12, 2004, 09:25 AM
 
Originally posted by H * £ £:
Does Apple ever proof view this stuff?
Think they'll ever notice the lame diagram and correct it?
No kidding, if that was accurate there would have to be a hole in the motherboard and the side of the case for the air to flow through. Even if you put a 90 degree bend in it, the air would be flowing backwards.

More than likely it is a over-generalization to illustrate how it basically works, the real thing could be a lot more complex.
     
dlefebvre
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Jun 12, 2004, 09:55 AM
 
     
macaddict0001
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Jun 12, 2004, 04:32 PM
 
Originally posted by jjqueenan:
This is moot.

First, Apple has never endorsed mounting G5s sideways that I know of. Virginia Tech stood them up. Any company doing otherwise isn't Apple's concern.

(Frankly I find most horizontal solutions, and purveyors therof to be just short of reprehensible).

I would assume that unless there is some kind of dip in the pipes (to give it some gravity) inside the radiator that it would not work properly if laid flat (and even then, which way?) or would advection then be the thing at work? Out of my field here...

Stand the damn things up and if you want rackables get Xserves

I can't stand seeing racked desktops anyway PET PEEVE
yeah it would screw up your tray loading superdrive anyway
     
klinux
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Jun 18, 2004, 03:08 PM
 
I was so sure it was just a heatpipe but guess I was wrong.

http://www.appleinsider.com/article.php?id=508
One iMac, iBook, one iPod, way too many PCs.
     
   
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