Ya know, if this isn't just another completely impractical weisenheimer brainstorm, but in fact, actually works - geez would that ever make Apple gosh darn, uh, cool ... the buzz factor alone would probably make people want to at least check the machines out.
Besides ...
I've got a bleedin' WinNT Vacuum cleaner next to my ear half the time - and worse, in the recording studio, there's nothing more annoying than wild ground hum or, when that incredible subtle detailed musical passage is about to happen (Imagine Arvo Part), and the 24bit 96K AD/DA illusion that you sold your kidney to hear is overwhelmed by the rising noise of cooling fans - like telling the girl of your dreams you make less money than she does ... it just breaks the spell.
Yes, Apple would do well to keep the dream alive with silent cooling!
The liquid (not necessary water) cooling system will work to transfer heat away from the processor(s) but fans will still be needed to expel the heated air from the case (plus there are other heat generators in the case other than the processor(s).)
I've got a bleedin' WinNT Vacuum cleaner next to my ear half the time
...
Yes, Apple would do well to keep the dream alive with silent cooling!
I second the motion. Fans are probably the loudest and least robust form of heat dissipation available. I find it likely that someday, no computers will have cooling fans. Moving parts are fragile and require periodic replacement.
A far better solution, although currently more expensive, is to use convection cooling. Convection cooling using only air has been proven in everything from the Cars (old VWs) to the G4 cube. It is also possible to use radiant cooling with closed, liquid-based systems. These resemble your typical, finned, aluminum heatsinks but have internal passageways through which liquid is circulated. It is possible to design these such that no pump is needed, with coolant circulation caused by the liquid being less dense when heated.
If any company can make closed-system, liquid-convection-cooled computers a reality, it would be Apple.
How much money do people pay to make their cars quiet? Many people would pay a ton of money to lower the average noise level of their lives by 20db. I spend a lot of time around computers and live with constant white noise.
Damn this athlon box under my desk and its 6 fans! I feel like I'm at a bleepin airport.
Apple can't break the laws of physics. If we rule out connecting a computer to the household water supply and a drain, any liquid cooling system must interface with the air to get rid of the heat. The only thing that liquid cooling does for you then is move heat from one place to another, and lets the heat transfer to the air somewhere else. The best Apple could do is have the liquid move the heat to the entire surface of the Mac case, and let the case be the interface to air fir carrying away the heat. Such a scheme does not seem practical, however. It would have little pipes running all around.
Consider the heat flow a dual 970 produces, almost 90 Watts just from the CPUs. To transfer heat to air, an object must get very hot in still air, like an incandescent light bulb, or the air must be moving. The faster the air movement the cooler the device will be. In the case of a CPU, it cannot be allowed to get too hot, so convection cooling is out.
So, I think we are stuck with a fan somewhere. But fans can be made quiet. A large, slow moving fans make much less noise. Think of a ceiling fan. Do you hear them running?
Where liquid cooling could pay off is in the size, shape and location of the heat sink. With a large, efficient heat sink, the air flow can be slower to achieve the same heat transfer. Whether it is worth the extra effort and cost is another question.
I think we will see thermoelectric (Peltier effect) based systems long before liquid-cooled systems. If you need to get lots of heat away from a small area pronto, there's nothing better. Their main drawback is efficiency - about 15% IIRC. So if you want to soak up 90 W off the processor, you'll have to dispel 600 W elsewhere. "Elsewhere", however, can be anyplace convenient, like a passive radiator at the back of the unit.
Purveyors of x86 hardware are way ahead of us in this area, for obvious reasons. Here's a link to some examples of TEC products:
. . . Their main drawback is efficiency - about 15% IIRC. So if you want to soak up 90 W off the processor, you'll have to dispel 600 W elsewhere. "Elsewhere", however, can be anyplace convenient, like a passive radiator at the back of the unit. . .
If that 15 percent efficiency is correct, this is not the way to go. Who wants a 600 Watt space heater in their room, especially in Summer?
If that 15 percent efficiency is correct, this is not the way to go. Who wants a 600 Watt space heater in their room, especially in Summer?
Amen to that. Peltier coolers are good for cooling down things that are well insulated and have a low heat load (x-ray detectors, infrared sensors and CCDs for example). They are not good heat pumps.
Some years ago I saw an engineering analysis showing that Peltier coolers for semiconductors was a bogus idea. You are better off just putting a heatsink and fan on the chip.
If that 15 percent efficiency is correct, this is not the way to go. Who wants a 600 Watt space heater in their room, especially in Summer?
Actually the efficiency of a peltier is more like 55%. Here is a link talking about some peltier calculations for an OC'ed Celeron up to about 40W, coincidentally.
If Apple used them (I don't think they would for other considerations) on a 970 they would be producing ~75W on the hot side. This still needs to be cooled, BTW.
The liquid (not necessary water) cooling system will work to transfer heat away from the processor(s) but fans will still be needed to expel the heated air from the case (plus there are other heat generators in the case other than the processor(s).)
Not necessarily. The problem with the heat from processors is that the heat sources are small and in a place determined by the circuit requirements, not by the cooling requirements. A water / liquid cooling system uses the medium to transport heat away from the processors to a heat exchanger that can be designed for optimal heat exchange. This means it can be larger / longer and positioned to take advantage of convective flow (is that a real word?!). Even if a fan is required it can have a much lower flow rate and thus be much quieter.
I agree, a fan may be needed (depending on case designs ability for natural convective cooling) to disperse the heat from the case but I wouldn't expect that a large fan would be required such as that needed to directly remove the heat from the fin-area of the CPU heat sink. (i.e., much smaller fans would be needed)
In HiFi amplifiers dissapation of large amount of heat can be done totaly passive by large heat sinks.The big Krells dissapate several hundred of watts. It is of course a way expensive item then a mere Macintosh...
One way for the Mac would be to have the part of the outer case made of metal that doubles as a heat sink. The CPU would then be either directly conected to this or having a small heat sink that docks into the metal case. In the latter case (pun intended) the motherboard could be docked in and out by closing and opening the door.
Sonly made HiFi amplifiers with cooling fluid circulation back in the 1990 or 1980 so there ought to be experience in long time reliability of such systems in consumer electronics (that is is made with severe cost constrains)
I think that these things are periferal features. The important thing is that we get a good CPU efter 4 years of G4 suffering!
Comments
Originally posted by JBL
Why not? 10.1 was a free upgrade. When 10.2 came out there was some discussion of the odd upgrades being free.
It won't be. Sorry . If you don't believe me, wait and see.
Originally posted by Programmer
http://www.scienceblog.com/community...rder=0&thold=0
May I be the first to say it?
"Cool"
Ya know, if this isn't just another completely impractical weisenheimer brainstorm, but in fact, actually works - geez would that ever make Apple gosh darn, uh, cool ... the buzz factor alone would probably make people want to at least check the machines out.
Besides ...
I've got a bleedin' WinNT Vacuum cleaner next to my ear half the time - and worse, in the recording studio, there's nothing more annoying than wild ground hum or, when that incredible subtle detailed musical passage is about to happen (Imagine Arvo Part), and the 24bit 96K AD/DA illusion that you sold your kidney to hear is overwhelmed by the rising noise of cooling fans - like telling the girl of your dreams you make less money than she does ... it just breaks the spell.
Yes, Apple would do well to keep the dream alive with silent cooling!
Originally posted by Programmer
http://www.scienceblog.com/community...rder=0&thold=0
Thank you, Programmer, for the excellent find. This, indeed, would be a cool cooling system.
Originally posted by OverToasty
I've got a bleedin' WinNT Vacuum cleaner next to my ear half the time
...
Yes, Apple would do well to keep the dream alive with silent cooling!
I second the motion. Fans are probably the loudest and least robust form of heat dissipation available. I find it likely that someday, no computers will have cooling fans. Moving parts are fragile and require periodic replacement.
A far better solution, although currently more expensive, is to use convection cooling. Convection cooling using only air has been proven in everything from the Cars (old VWs) to the G4 cube. It is also possible to use radiant cooling with closed, liquid-based systems. These resemble your typical, finned, aluminum heatsinks but have internal passageways through which liquid is circulated. It is possible to design these such that no pump is needed, with coolant circulation caused by the liquid being less dense when heated.
If any company can make closed-system, liquid-convection-cooled computers a reality, it would be Apple.
How much money do people pay to make their cars quiet? Many people would pay a ton of money to lower the average noise level of their lives by 20db. I spend a lot of time around computers and live with constant white noise.
Damn this athlon box under my desk and its 6 fans! I feel like I'm at a bleepin airport.
[edit: quite != quiet]
Consider the heat flow a dual 970 produces, almost 90 Watts just from the CPUs. To transfer heat to air, an object must get very hot in still air, like an incandescent light bulb, or the air must be moving. The faster the air movement the cooler the device will be. In the case of a CPU, it cannot be allowed to get too hot, so convection cooling is out.
So, I think we are stuck with a fan somewhere. But fans can be made quiet. A large, slow moving fans make much less noise. Think of a ceiling fan. Do you hear them running?
Where liquid cooling could pay off is in the size, shape and location of the heat sink. With a large, efficient heat sink, the air flow can be slower to achieve the same heat transfer. Whether it is worth the extra effort and cost is another question.
Purveyors of x86 hardware are way ahead of us in this area, for obvious reasons. Here's a link to some examples of TEC products:
http://www.cooltechnica.com/Merchant...egory_Code=TEC
Originally posted by Bigc
Where do you get 90 watts for two 970 CPU's?
42W @ 1.8 GHz, 1.3v
19W @ 1.2 GHz, 1.1v
PPC970_MPF2002.pdf
Originally posted by Amorph
Actually, if memory serves, the IBM release that touted speeds up to 2.3GHz still mentioned a 900MHz bus.
The relative clock speed design makes sense, but now that I think about it, I can't remember if it came from any other source than these boards.
Anyone got a link?
The basic heartbeat of the bus is 450MHz, with DDR signaling being used to make an effective 900MHz signaling rate.
3 * 450 MHz = 1350 MHz (~1.4GHz)
4 * 450 MHz = 1800 MHz (1.8GHz)
5 * 450 MHz = 2250 MHz (~2.3GHz)
so I would say that a simple multiplication of the 450MHz reference frequency is what drives the core clock rates that have been mentioned thus far.
Originally posted by Bigc
Where do you get 90 watts for two 970 CPU's?
I said almost 90 Watts. I seem to remember they are 42 Watts each at 1.8 GHz. I guess I could have said "over 80 Watts."
Originally posted by TJM
. . . Their main drawback is efficiency - about 15% IIRC. So if you want to soak up 90 W off the processor, you'll have to dispel 600 W elsewhere. "Elsewhere", however, can be anyplace convenient, like a passive radiator at the back of the unit. . .
If that 15 percent efficiency is correct, this is not the way to go. Who wants a 600 Watt space heater in their room, especially in Summer?
Originally posted by snoopy
If that 15 percent efficiency is correct, this is not the way to go. Who wants a 600 Watt space heater in their room, especially in Summer?
Amen to that. Peltier coolers are good for cooling down things that are well insulated and have a low heat load (x-ray detectors, infrared sensors and CCDs for example). They are not good heat pumps.
Some years ago I saw an engineering analysis showing that Peltier coolers for semiconductors was a bogus idea. You are better off just putting a heatsink and fan on the chip.
Originally posted by snoopy
If that 15 percent efficiency is correct, this is not the way to go. Who wants a 600 Watt space heater in their room, especially in Summer?
Actually the efficiency of a peltier is more like 55%. Here is a link talking about some peltier calculations for an OC'ed Celeron up to about 40W, coincidentally.
http://www.overclockers.com.au/techstuff/29oct99.shtml
If Apple used them (I don't think they would for other considerations) on a 970 they would be producing ~75W on the hot side. This still needs to be cooled, BTW.
MM
Originally posted by Bigc
The liquid (not necessary water) cooling system will work to transfer heat away from the processor(s) but fans will still be needed to expel the heated air from the case (plus there are other heat generators in the case other than the processor(s).)
Not necessarily. The problem with the heat from processors is that the heat sources are small and in a place determined by the circuit requirements, not by the cooling requirements. A water / liquid cooling system uses the medium to transport heat away from the processors to a heat exchanger that can be designed for optimal heat exchange. This means it can be larger / longer and positioned to take advantage of convective flow (is that a real word?!). Even if a fan is required it can have a much lower flow rate and thus be much quieter.
One way for the Mac would be to have the part of the outer case made of metal that doubles as a heat sink. The CPU would then be either directly conected to this or having a small heat sink that docks into the metal case. In the latter case (pun intended) the motherboard could be docked in and out by closing and opening the door.
Sonly made HiFi amplifiers with cooling fluid circulation back in the 1990 or 1980 so there ought to be experience in long time reliability of such systems in consumer electronics (that is is made with severe cost constrains)
I think that these things are periferal features. The important thing is that we get a good CPU efter 4 years of G4 suffering!