Are we looking at iMac design the wrong-way-about?

[jsolares]

I was thinking of your comments and I remembered that the Alaskan pipeline is cooled by heat pipes to maintain the permafrost under supporting pillars. In checking on this I found laptops may have heat pipes in connection with their heat sinks <http://en.wikipedia.org/wiki/Heat_pipe>. The copper tubes are heat pipes connected to a radiator:

[I was unable to upload this image it doesn’t have an HTTP address]

A different system is show in a laptop connecting two solid interfaces:

[I was unable to upload this image—go to the URL above]

The heat pipes contain a gas whose density is adjusted to be effective as a refrigerant, vaporized at the site to be cooled and condensing at the target interface, as in a common refrigerator.

Note, however, that these strategies, where used, move or spread out hot-spot conditions within the computer: getting the heat outside the computer is the job of convection in iMacs. The aluminum case plays its part, too, but without convection cooling the iMac would be in deep trouble.

All apple products use heat pipes, even the Mac Pro uses them on the cpu heat sink to distribute heat over it.

On the 27" 2010/2011 models they're used because in essence you have 3 channels of air made by the 3 fans in there, so the heatpipes are used to move the heat from the cpu/gpu over to where their respective fans blow air.

You can even see the heatpipe tubing on the picture posted of the 2012 model, what i can't make out is where the gpu is exactly.

The fan position on the 2012 is indeed weird as it's pushing air downwards against the heat, instead of upwards like on recent imacs, will be interesting to see how it works out.

 

[Tucson Allen]

Sometimes less is more

I think you're being overly optimistic. The iMac, pretty much since its late 2005 redesign has been steadily on a course to become thinner than necessary and while the CPUs used since the PowerPC 970FX (G5) and the Intel Core Duo have also dropped in heat requirements since then, they haven't by THAT much. Really, the whole point to the iMac is to save space where the whole point to an actual proper desktop is to utilize it. Toward that end the iMac has become increasingly unreliable. I work at an Apple Authorized Service Provider and the iMac is the #1 machine that comes in for non-accidental-damage. I'm confident that what will effect the most positive change in terms of heating and reliability will be the change to 2.5" hard drives and other laptop based components in the 21.5" iMac. Sure from a functionality standpoint it is a downgrade; but it terms of it being a reliably long-lasting machine, I think it has just made some serious headway. As for the 27" iMac, I don't care where you position the fans, there are a lot of heat generating components in that machine. There always have been. But now they've removed one component (along with a couple fans, if I understand correctly) that didn't really generate all that much heat, kept all of the other heat-generating components just the same and made it thinner, if not way thinner than would otherwise negate the removal to begin with. So really, we might have a LESS reliable and MORE hot-running 27" iMac than before. It's all conjecture as these machines aren't out yet, and thusly they are not in my shop for repair yet, but I'm not overly confident in the 27" iMac. But 21.5" iMac, I'm very much hopeful that I can start confidently recommending them to people that would otherwise buy the Mac mini but want more ooomph.

The post indicates, as far as I can see, that writer will engineer a hackintosh superior in performance and durability to the new iMacs we are waiting for. Do hackintosh designs rely on Darwin? Are they equivalent in OS upgradability? Are they all but Mac Pros except for the price? I am not trying to funny here. Without doubt more powerful components may be chosen in a tower, and they may be assembled with equivalent deftness. But the fact is all design is compromise. Good design means these compromises in their effect may be said to imply a decent level of talent, which can rise on occasion to genius. The all-in-one form factor of these iMacs denies the freedom of choice in a tower design: apples and oranges.

The post shows that its writer strongly disapproves of the “unnecessary“ thinness of the edge. Good industrial design makes sales, and if it is good design indeed, its function will live up to its style, and its performance will be improved. There are other threads in MacRumors that show that iMac design has largely performed and endured. As to style, I’d say we are looking at a smashing success. It will be an icon in an established iconic tradition. As for endurance, I for one think the technical design harks back to the 15” iMac D (G3 333 MHz), which was cooled by convection only, having no fan at all. (I owned one. It was still working when I replaced it.) Its style was a stark contrast to any notion of “thin.“ Its design was outwardly no different from the earlier models, but the interior was changed such that it could do away with fans entirely without suffering loss of performance. In the Apple design tradition, then, due thought is given to the role of convection when the occasion arises.

In the present iMac there was a direction given, a decision made, that it should have a thin edge, whether at the engineering-designer level or from above. Room had to made for the components. The designer chose to make a gradual bulge buildup in the center, making room for the larger components—and then some. The designer shaped the bulge in such a way as to control and channel the flow of the heat/pressure/velocity of the convection effect, even to make the hottest air at the top flow down to the vent in the lower middle, aided by the central fan discharge.

Just as a chimney is a better exhaust form than open windows upstairs from a warm living room and a cellar below, the channeling at the center of the heat by-products can improve the velocity of the flow in contrast to the flow from the bottom intakes to the top slits of the older iMacs. The hot-spots in the old system do not channel, confine, the movement of the air to the vents. The heat pipes and heat sinks are designed to spread out the heat, but not to channel it. The fans channel there largely effect the hot spots. They have little effect on venting to the outside. The old style was a chimney only in the sense that the air movement is generally upward and the heat sources along the way enhance that tendency. This lacked the more channelled effect of the new iMac. Its flows to either side meet at the narrowing top. There the spatial gradient at the center of the rising hump creates a partial vacuum as the hot air encounters more space. The increase in available space continues to cause a pressure drop and to move the air downward until the hump rises to its maximum and begins to fall way after the vent. Behind all this is the force of the rising currents on either side being accelerated by the pressure changes leading the downward flow to the vent. After the vent there is a contrary effect on the pressure/temperature/velocity quantities. Thus the downward impulse is felt all along the line and a counter flow at the center is created leading to the vent.

In this way less total space can lead to improved cooling.

 

[Yebubbleman]

The post indicates, as far as I can see, that writer will engineer a hackintosh superior in performance and durability to the new iMacs we are waiting for. Do hackintosh designs rely on Darwin? Are they equivalent in OS upgradability? Are they all but Mac Pros except for the price? I am not trying to funny here. Without doubt more powerful components may be chosen in a tower, and they may be assembled with equivalent deftness. But the fact is all design is compromise. Good design means these compromises in their effect may be said to imply a decent level of talent, which can rise on occasion to genius. The all-in-one form factor of these iMacs denies the freedom of choice in a tower design: apples and oranges.

Here's what goes into taking a Hackintosh running 10.8.1 to 10.8.2: instead of going to the Apple Menu and selecting "Software Update" thusly triggering the Mac App Store (as the modern day replacement to the standalone "Software Update" app of 10.7 and earlier) and then downloading the 10.8.2 update from there, a 10.8.1 Hackintosh user downloads the delta update from Apple's support site and installs it that way. It will prompt him or her to restart the computer in order to finish the installation. Before doing so, all of the kernel extensions (KEXT files), drivers, and/or patches that were in place before the update must be reapplied. Depending on what guide was followed and what hardware was picked, this will be anywhere from quick and easy to long and involved; your mileage will vary. Once that is done, then Disk Utility must be launched and permissions must be verified and repaired. Once that is all done, the user may reboot the computer and assuming everything was done properly the Hackintosh will boot to a fully functional and otherwise-identical-to-the-real-thing version of OS X 10.8.2. There are programs to simplify that step, let alone programs that can be made to automate this process per patch, but most people Hackintoshing tend to not invest all that much time into saving time (ironically enough). Otherwise, Hackintoshes, using Intel CPUs no older than some form of Core 2 and an OS no older than Snow Leopard, can enjoy the use of the stock retail Darwin kernel. Enterprising AMD users and users of either older Intel hardware or older OSes than Snow Leopard will often need to use a custom kernel.

Otherwise, while Apple may have been able to make a creatively designed computer, if it isn't practical, then it's a stupid design. The whole point of buying an iMac over a MacBook Pro is that additional oomph is offered. If I max out a 15" non-retina MacBook Pro, I get much more of a machine than I would out of a base model high-end 21.5" iMac. Sure, I'm paying double for the MacBook Pro, but technologically, the iMac doesn't, at that point offer me anything that sets it apart from the MacBook Pro save for price savings. The 27" iMac could trump in that kind of an argument, but not by a whole lot. A faster CPU, quadruple the maximum RAM, yes. But expandability (it is a desktop after all), the ability to give it even more powerful graphics or even more storage? This is what makes the iMac a stupid design. Even if cooling efficiency in these new models makes the problems of the older models non-existent, it's still much more form than function and much more compromise than power.

The post shows that its writer strongly disapproves of the “unnecessary“ thinness of the edge. Good industrial design makes sales, and if it is good design indeed, its function will live up to its style, and its performance will be improved. There are other threads in MacRumors that show that iMac design has largely performed and endured. As to style, I’d say we are looking at a smashing success. It will be an icon in an established iconic tradition. As for endurance, I for one think the technical design harks back to the 15” iMac D (G3 333 MHz), which was cooled by convection only, having no fan at all. (I owned one. It was still working when I replaced it.) Its style was a stark contrast to any notion of “thin.“ Its design was outwardly no different from the earlier models, but the interior was changed such that it could do away with fans entirely without suffering loss of performance. In the Apple design tradition, then, due thought is given to the role of convection when the occasion arises.

In the present iMac there was a direction given, a decision made, that it should have a thin edge, whether at the engineering-designer level or from above. Room had to made for the components. The designer chose to make a gradual bulge buildup in the center, making room for the larger components—and then some. The designer shaped the bulge in such a way as to control and channel the flow of the heat/pressure/velocity of the convection effect, even to make the hottest air at the top flow down to the vent in the lower middle, aided by the central fan discharge.

Just as a chimney is a better exhaust form than open windows upstairs from a warm living room and a cellar below, the channeling at the center of the heat by-products can improve the velocity of the flow in contrast to the flow from the bottom intakes to the top slits of the older iMacs. The hot-spots in the old system do not channel, confine, the movement of the air to the vents. The heat pipes and heat sinks are designed to spread out the heat, but not to channel it. The fans channel there largely effect the hot spots. They have little effect on venting to the outside. The old style was a chimney only in the sense that the air movement is generally upward and the heat sources along the way enhance that tendency. This lacked the more channelled effect of the new iMac. Its flows to either side meet at the narrowing top. There the spatial gradient at the center of the rising hump creates a partial vacuum as the hot air encounters more space. The increase in available space continues to cause a pressure drop and to move the air downward until the hump rises to its maximum and begins to fall way after the vent. Behind all this is the force of the rising currents on either side being accelerated by the pressure changes leading the downward flow to the vent. After the vent there is a contrary effect on the pressure/temperature/velocity quantities. Thus the downward impulse is felt all along the line and a counter flow at the center is created leading to the vent.

In this way less total space can lead to improved cooling.

Apple's achievement of minimizing cooling requirements while making the machine thinner (a) isn't as amazing as you think (again, they're making the 21.5" iMac basically a low-end 15" non-retina MacBook Pro with a desktop CPU), and (b) is trivial compared to what the design of a desktop should be aiming for (namely increased functionality).

Sure, Apple threw money at making the cooling more efficient. Though they could've also done that by making the machine thicker and in the process they would've increased upgradability, longevity, functionality, and it would be no less beautiful a computer. Really, marveling at their design this way is really no different than trying to crap two car loads of crap into one car when another car is readily available for the purpose. What's the point?

 

[Tucson Allen]

Cooled by intelligently managed convection

In concentrating on the left and right flows moving upward and merely noting a centering bias, I neglected a follow-up on the centering bias, which turns out to be more important and stronger than the up-flows to the sides. It yields more significant cooling.

The centering tendency is caused by the (at first) gently rising slope to the center. An increment of gas as it ascends is supported on all sides by neighboring packets of gas. In a simplified view, its neighbor moving to the center (on a bias) occupies a larger volume at a reduced pressure because of the increase in altitude under the slope of the back. This change in volume is necessarily accompanied by changes in the pressure/temperature values (Boyle’s Law). Our packet being faced with a (very) partial vacuum on a center bias tends to follow in its neighbor’s path. Thus we are looking at time and motion in little. In fact this only represents one active link in a chain of such links, each packet being connected to the next in their motions and defined by their motions. This overall motion is connected in time as well, registering changes in velocity.

Looked at in this way, from the time a packet becomes a part of a thread by being drawn into the iMac, until a packet in the thread is pushed out of the iMac at the vent, all packets forming the thread are interconnected: this is implicated by the effects of the motion. An increase or decrease in speed is felt all up and down the line. Any heat taken on increases the process. A change in volume follows the temperature/pressure complex; this is felt only locally, but it is implicated in the other changes. As a packet approaches the dome this process is dramatically increased. Reaching the arch of dome necessarily ends the cross-flows in their meeting. Then the increasing altitude of the dome up to the vent draws the thread flow downward. The downflows from the top merge with the side flows moving to the vent.

These effects are heightened where heat sources are encountered: the more heat, the greater the effect. Thus the heat empowers the cooling process of air movement and directs it where it is most needed. The venting to the outside provides the final added thrust moving the whole convection machine. There is no evaporative cooling, except in the heat pipes terminating at their heat sinks. There is a degree of radiant cooling, revealed in the warming of the aluminum case (note that the aluminum is not connected to the hot components to render any significant cooling by conduction). You might say the iMac is cooled by intelligently managed convection.

The teardrop shape of the lower dome below the vent has a similar centering bias, possibly with less effect until there are heat sources to encounter. The air, rising from the vents under it and near it, will tend to migrate up the dome to the vent as they encounter heat sources. The entire volume of the case experiences an overall flow to the vent that creates a drop in pressure at the intakes, drawing air in. At the vent all flows come together. The downward flow from above is discouraged from continuing downward by the dome‘s falling away, tending to generate a pressure block. The upward flow from below the vent would also tend to block the flow from above the vent. The vent itself tends to create a pressure drop in the face of all flows ending near it, enforcing a movement to the vent and out. This movement of the air to the outside creates a partial vacuum system wide: the chimney “draws,” the iMac is cooled. The fan’s action in this is primarily local, not being coupled in any special way to the vent.

I can’t wait to see the first tear-down and review of the 21.5!

I add some URLs for illustration. I have not yet been able to upload from Wikipedia to this post:

<http://en.wikipedia.org/wiki/Franklin> —the original stove using a reversed flow flue: down, then up
I was unable to find his downdraft fire place with flue under the floor leading to a chimney in the wall, which I cited in another thread

<http://www.permies.com/t/4807/stoves/rocket-mass-heater-uses-less>
a stove fired through an open top with reversed flue

 

[Tri-stan]

Apple's achievement of minimizing cooling requirements while making the machine thinner (a) isn't as amazing as you think (again, they're making the 21.5" iMac basically a low-end 15" non-retina MacBook Pro with a desktop CPU), and (b) is trivial compared to what the design of a desktop should be aiming for (namely increased functionality).

The 21.5 inch iMac in this picture still seems to be built of the same size of components as the 27 inch and not quite srinked to the level of a mbp bar hdd. As I said before in my comment (like an enhanced mbp) Using more robust components the iMac should be more likely to resist heat due to their increased size. I can't speak for the exact physics of this principle thought this is the general idea.

So in terms of the relationship to a mbp yes you are right here it is a different computer in some ways but not entirely different. It just has a different level of component density. Everything else is more or less serves the same function at a different level of density and power.

Sure, Apple threw money at making the cooling more efficient. Though they could've also done that by making the machine thicker and in the process they would've increased upgradability, longevity, functionality, and it would be no less beautiful a computer. Really, marveling at their design this way is really no different than trying to crap two car loads of crap into one car when another car is readily available for the purpose. What's the point?

I still think it is the right direction to go by reducing the size of the machine. This is an all in one not a tower pc. For a start its going to make moving the machine around very easy to do which some users do with the iMac. As long as the performance and reliability can be improved upon I see no reason why slim and thin is a bad idea. It is reducing the amount of materials going in to the device no end. If the new iMac can prove that slimmed down components can be met with greater reliability then environmentally speaking the idea of reducing the size and power consumption is a positive improvement and for the iMac a progressive improvement. I am already sold on the aesthetics of the new machine I now wait to see how it performs.

I would like to see the iMac more easily open-able for the consumer to change parts at will. The use of magnets behind the screen could be pushed further to make it super easy to get at the parts required to be changed or lightly upgraded. If anything a way of gaining access for the more advanced user. It would be nice to see some streamlining of that the overall procedure to open the case and change parts. There is already less parts in this new iMac so the procedure will be reduced somewhat.

 

[unfrostedpoptar]

I think you are trying to make this cooling system too complicated. I agree with the principle of convection but what you are referring to is the 2011 iMac. It used the exact process you are talking about. The the 2013 relies much less on convection and lets the central fan do most of the work. If you look closely on the internal case shot there is an inlet for the fan at the top of the case which draws air in to be blown down a tube to the center point of the case. This happens to align with the slot under the case stand which will indefinitely be the place where air is forced out of the machine via the fan.

Convection is only a weak force when confined to such a small space as the iMac. It would be next to useless to use convection with a small exit in the center of the case. This would defeat the hole point of rising hot air. Hence why the 2011 iMac has a long slot gap running across the entire length of the top of the case. I assure you nearly all laptops have air channels to blow hot air thought the case chassis and it will work perfectly fine for the iMac unit. You will be able to physically feel the hot air coming out of like a hairdryer, convection does not have such an effect in this situation.

I know that the 2011 iMac 27" uses convection a fair amount. A few weeks ago, I rotated it to portrait orientation (it's mounted on an ARM using Apple's VESA adapter). I really like it this way but the fan definitely comes on a lots more than it used to!

 

[Tucson Allen]

I wonder if it is a production model?

Image

The 21.5 inch iMac in this picture still seems to be built of the same size of components as the 27 inch . . . .

. . . As long as the performance and reliability can be improved upon I see no reason why slim and thin is a bad idea. It is reducing the amount of materials going in to the device no end. If the new iMac can prove that slimmed down components can be met with greater reliability then environmentally speaking the idea of reducing the size and power consumption is a positive improvement and for the iMac a progressive improvement. I am already sold on the aesthetics of the new machine I now wait to see how it performs.

. . .

The Macrumors news article, October 14, 2012 4:28 am PDT by Eric Slivka, shows this image. The article deals with the question of its authenticity. A Hardmac article, http://www.hardmac.com/news/2012/10/16/picture-of-the-new-imac, notes that the HDD is a 2.5 one, suggesting at the present time that it is a 21.5 model. The details are considerably different. The HDD is to the left. The RAM is not visible. A discharge to the fan is not shown; it seems to be headed to the rear of the case. The component boards a very different. The bottom of the view is missing, hiding the connectivity details.

Some of this accords to the info we’ve been given, i.e., RAM not user upgradable, a 2.5” HD. The boards however seem to take up much more space and perhaps speak to a different style of design. It lacks the aesthetic tidiness and trim economy of the 27 model. The turning around of the fan discharge is a complete mystery. I wonder if it could be an actual production model of the new 21.5? Possibly it is a late prototype?

I’m waiting for the first tear downs and reviews of the 21.5. Eagerly.

 

[Tri-stan]

The Macrumors news article, October 14, 2012 4:28 am PDT by Eric Slivka, shows this image. The article deals with the question of its authenticity. A Hardmac article, http://www.hardmac.com/news/2012/10/16/picture-of-the-new-imac, notes that the HDD is a 2.5 one, suggesting at the present time that it is a 21.5 model. The details are considerably different. The HDD is to the left. The RAM is not visible. A discharge to the fan is not shown; it seems to be headed to the rear of the case. The component boards a very different. The bottom of the view is missing, hiding the connectivity details.

Some of this accords to the info we’ve been given, i.e., RAM not user upgradable, a 2.5” HD. The boards however seem to take up much more space and perhaps speak to a different style of design. It lacks the aesthetic tidiness and trim economy of the 27 model. The turning around of the fan discharge is a complete mystery. I wonder if it could be an actual production model of the new 21.5? Possibly it is a late prototype?

I’m waiting for the first tear downs and reviews of the 21.5. Eagerly.

This is the 21.5 inch model with the screen taken out. All the other views I have put up on here shows the 27 inch theoretically from the back. There is no way it can be shown like this but rather it is just an x-ray view through the back of the aluminium case. The whole aluminium case is molded together and is only assailable/view-able through the front case opening.

 

[Tucson Allen]

This is the 21.5 inch model with the screen taken out. All the other views I have put up on here shows the 27 inch theoretically from the back. There is no way it can be shown like this but rather it is just an x-ray view through the back of the aluminium case. The whole aluminium case is molded together and is only assailable/view-able through the front case opening.

That’s interesting. It puts the HDD on the right, further down √; the fan on the left, and the discharge works. I seem to remember seeing the fan on the left in a view, but I couldn’t find it again. The screw are sure enough out of the plastic thingies, indicating disassembly √. I think you’ve got it.

----------

This is the 21.5 inch model with the screen taken out. All the other views I have put up on here shows the 27 inch theoretically from the back. There is no way it can be shown like this but rather it is just an x-ray view through the back of the aluminium case. The whole aluminium case is molded together and is only assailable/view-able through the front case opening.

That’s interesting. It puts the HDD on the right, further down √; the fan on the left, and the discharge works. I seem to remember seeing the fan on the left in a view, but I couldn’t find it again. The screw are sure enough out of the plastic thingies, indicating disassembly √. I think you’ve got it.

 

[Yebubbleman]

Image

The 21.5 inch iMac in this picture still seems to be built of the same size of components as the 27 inch and not quite srinked to the level of a mbp bar hdd.

First off, there's only one clear picture of the internals of the new 27" iMac, and it's the one used in the keynote. Secondly, those internals differ wildly from what is pictured here. Yes, the logic board retains the same basic shape. Shocker! It's the same basic shape externally too! Coincidence??? Not even kind of. To compare logic board shapes is stupid, they have custom shapes to go in custom enclosures. And yes, that is a 2.5" hard drive; the exact same hard drive type that you'd find in a non-retina MacBook Pro. The 27" iMacs still use 3.5" drives.

As I said before in my comment (like an enhanced mbp) Using more robust components the iMac should be more likely to resist heat due to their increased size. I can't speak for the exact physics of this principle thought this is the general idea.

The components in an iMac are no more robust than they are in a MacBook Pro. It's still circuitry designed to be environmentally friendly, which actually makes it LESS robust and LESS likely to resist heat. As for your physics, no offense, but I really don't think you know what you're talking about here.

So in terms of the relationship to a mbp yes you are right here it is a different computer in some ways but not entirely different. It just has a different level of component density. Everything else is more or less serves the same function at a different level of density and power.

We can't talk about nonsensical topics like component density on a product that isn't out yet. Even if we could, talking about it in terms of component density and not in terms of heat vs. thermal envelope would do nothing. The shape of the boards and screens has no bearing on the sizes of the components generating the most heat.

I still think it is the right direction to go by reducing the size of the machine. This is an all in one not a tower pc. For a start its going to make moving the machine around very easy to do which some users do with the iMac.

This is only useful for thieves and people who work with rentals or move around a lot. If you move around a lot, an iMac is a poor choice anyway. I work with rentals on occasion, and while it'd be nice to have a lighter iMac for those applications, it's a desktop; the point of it isn't to be light, it's to be powerful.

As long as the performance and reliability can be improved upon I see no reason why slim and thin is a bad idea.

That's the thing though, performance and reliability are NOT improved that way, they're worsened. a 21.5" iMac now uses a 2.5" hard drive instead of a 3.5" drive. This worsens performance but increases reliability. You can't have your cake and eat it too with this stuff. To have a desktop that is as emaciated as the iMac is, you need to make compromises and no, these compromises do not make for both performance and reliability.

It is reducing the amount of materials going in to the device no end. If the new iMac can prove that slimmed down components can be met with greater reliability then environmentally speaking the idea of reducing the size and power consumption is a positive improvement and for the iMac a progressive improvement. I am already sold on the aesthetics of the new machine I now wait to see how it performs.

You are way too optimistic and naive about this. Yes the aesthetics of the machine are great. Try actually servicing or upgrading one before you sing its praise too loudly.

I

would like to see the iMac more easily open-able for the consumer to change parts at will. The use of magnets behind the screen could be pushed further to make it super easy to get at the parts required to be changed or lightly upgraded. If anything a way of gaining access for the more advanced user. It would be nice to see some streamlining of that the overall procedure to open the case and change parts. There is already less parts in this new iMac so the procedure will be reduced somewhat.

Again, optimism and naiveté. They're not bad qualities to have, but you'll soon learn that none of these hopes of yours will come to fruition. The iMac has never been a great machine in these regards, and this will only get worse. History has shown this much.