|
|
#26 | |
|
Quote:
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.
__________________
iMac 27" 2010 i5 2.8ghz; Macbook Air 13" 2011 i5 |
||
|
|
0
|
|
|
#27 | |
|
Sometimes less is more
Quote:
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. |
||
|
|
0
|
|
|
#28 | ||
|
Quote:
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. Quote:
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?
__________________
MacBook Pro (15" Mid 2012); PC Tower (3.4GHz Phenom II x4; Radeon HD 6850); 5th Gen iPod touch Blue 64GB; 3rd Gen tv; 1st Gen iPad Wi-Fi 32GB; Galaxy Nexus LTE"Don't Cry, Eat Pie" |
|||
|
|
0
|
|
|
#29 |
|
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 Last edited by Tucson Allen; Nov 14, 2012 at 03:27 PM. Reason: grammar |
|
|
|
0
|
|
|
#30 | ||
|
Quote:
![]() 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. Quote:
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.
__________________
Traded in a custom windows box, core i7 3770K, vertex 3 ssd+hdd, 16gig ram, quadro 2000, u2711 monitor | 27" iMac, i7, 675MX, 1TB HDD With SSD Upgrade |
|||
|
|
0
|
|
|
#31 | |
|
Quote:
|
||
|
|
0
|
|
|
#32 | |
|
I wonder if it is a production model?
Quote:
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. Last edited by Tucson Allen; Nov 14, 2012 at 06:02 PM. Reason: missing words |
||
|
|
0
|
|
|
#33 | |
|
Quote:
__________________
Traded in a custom windows box, core i7 3770K, vertex 3 ssd+hdd, 16gig ram, quadro 2000, u2711 monitor | 27" iMac, i7, 675MX, 1TB HDD With SSD Upgrade |
||
|
|
0
|
|
|
#34 | ||
|
Quote:
---------- Quote:
Last edited by Tucson Allen; Nov 14, 2012 at 06:57 PM. Reason: title missing: I think you’re right! |
|||
|
|
0
|
|
|
#35 | |||||||
|
Quote:
Quote:
Quote:
Quote:
Quote:
Quote:
I Quote:
__________________
MacBook Pro (15" Mid 2012); PC Tower (3.4GHz Phenom II x4; Radeon HD 6850); 5th Gen iPod touch Blue 64GB; 3rd Gen tv; 1st Gen iPad Wi-Fi 32GB; Galaxy Nexus LTE"Don't Cry, Eat Pie" |
||||||||
|
|
0
|
![]() |
|
«
Previous Thread
|
Next Thread
»
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
All times are GMT -5. The time now is 01:21 AM.







tv; 1st Gen iPad Wi-Fi 32GB; Galaxy Nexus LTE
Linear Mode
