You could be right. Your experience with 21.5 and 27 iMacs is extremely helpful. I am assuming that the thin-edge design made a fundamentally changed approach to the convection chimney necessaryand that this led to an opportunity for a brilliant improvement in design functionality. With the thin edges the central hump could be formed into a convection engine. Thinking in terms of Boyles Law, heating a gas results not merely a temperature change but also involves a pressure change such that if confined in a constant volume, the gas registers an increase in pressureor, if the gas is free to expand, it will expand with a corresponding temperature drop. This made the thinness a virtue, giving the heated gas a centering bias, and the gasairrising to the top, a downward thrust, reenforced by the fan.
The shape of the hump is complex, likened to a teardrop. The point of maximum extension of the back occurs at the vent screen. This means that all flows come together here, the pressured flows acting as thrust. Because of the venting the micro effect is a local pressure drop, reinforcing the complex flow patterns. I judge that the vent size is tuned to maximize the flow-through of the enclosure. A vent too large could stultify the desire convection actions.
The expanding heated air does not exit via the intakes in the chin at the bottom. The general tendency of the air inside as its being heated is to rise, creating a partial vacuum at the intakes, helped by their being made of aluminum, an excellent conductor of heat. This causes the air-intake tubes to play a part in the overall chimney effect.
I think its an outstanding design. This doesnt mean that it solves the heat problem of the previous iMacs, but the very quality of the design implies a very knowledgeable designer. Intuitively I register the fact that only one fan is used where two were before is an indication that the other fan isnt neededbecause cooling and venting has been substantially improved. The 5400 rpm HDD in the 21.5 iMac indicates to me that something about the smaller design made the cooler operation of the (more expensive) drive necessary. There is at present no indication that a second fan is necessary. These conjectures lead me to think the 27 iMac is really improved in its heat management. In a way, the 27 iMac has a longer chimney, more room to accelerate the flows. But in the 21.5, which I intend to order, the 5400 rpm drive cant be far behind with its cooler CPU and GPU.
No doubt these computers were designed by ACTUAL engineers. However, that doesn't at all mean that the engineers were given poor designs. Similarly the designers may very well know a thing or two about engineering, but that doesn't mean that they made the right design decisions in designing.
The iMac has always been a form over function exercise in needless minimalism. If we can shave the total volume down, we will and for no other reason other than to stroke our own ego and make it look externally pretty at the expense of internal practicality and elegance.
That being said, the 21.5" iMac won't have improved in terms of its thermal problems for any other reason other than Apple further neutering it so that the power it outputs finally matches its thermal envelope. That being said, in the 27" iMac, most of these problems haven't been addressed as the only component removed is the optical drive and that machine was made well thinner than the thickness of that drive. These machines won't see thermal improvement from simply rearrangement; they need to use weaker components in order for it to fit and not cause problems. Again, hence the 2.5" 5400RPM drive in lieu of the 3.5" 7200RPM drive. This is also why every video card in the 21.5" iMac is a GT whereas every video card in a 27" iMac is a GTX, a disparity not previously seen between these two iMacs.
If what you want is a computer that will last and be at all utilitarian, the iMac is a terrible machine. If what you want is a computer that is externally gorgeous with no interest in how ugly it is on the inside and what problems may arise from such a design, it'll make you happy. Personally, I'll skip it and make a Hackintosh instead (or just simply use my non-retina 15" MBP as that machine has none of the design failures that plague the iMac).
For reference:
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For anybody reading this the re-designed 2012 iMac is effectively an enhanced MacBook Pro. Same simple design like the mbp the iMac has now got a logic board with cpu, gpu, msata, ram, cooling fan and exhaust outlet. Separate power supply, speakers and hdd. Other components like WiFi, Bluetooth, IR sensor cannot be seen on this image. There is not special cooling system here just an oversized mbp strapped on to an improved cinema display. If the reliability of laptops and the mbp's is anything to go by the new iMac is a more encompassing cooling system that we can expect at least to be on par with the mbps. As long as you are not rendering, encoding or gaming for long sessions all the time then I could expect great things from this revised iMac wth cool running componants at idle..
Some of these ideas for cooling systems, especially the positive charged cooling system looks promising for future designs.
For one, the 27" iMac is not a MacBook Pro, not in terms of design, not in terms of engineering, not in terms of anything. Secondly, that picture you have is of the 27" and not the 21.5". While in terms of components, you're likely right about the 21.5" iMac (save for the CPU), you're completely wrong when it comes to the 27" iMac. Desktop components are very much different from laptop components in terms of how much power they draw, how much heat they generate and how they can be designed when stuffed into such a stupidly thin package.
Oh, there's the picture. I was reading this thread earlier wondering where a picture was, and couldn't be bothered to search for one.
Someone said earlier about those black things on the right and left (The things with the large round holes and gaps on the bottom?) I think those are definitely the speakers.
Unless we're talking about the much larger black things on the right and left? Can't think of what those are.
Well, I'll be using it for those things pretty much...except gaming...don't really game much.
I would link to my most recent video (To demonstrate what I regularly do) but I don't want people to go off topic and talk about how bad it is (You need the balls to show it to a forum and then people like to go completely offtopic* and move over to talking about the video).
I think I might get an external Thunderbolt graphics card if the new iMac doesn't handle it that well...I think it should hold out well because it's CUDA certified (So excited to try CUDA).
*I'm now going offtopic...
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I'm not entirely sure, I'm not the one t be getting real answers from on this, but I think I remember about a month after the 15" Retina release, there were reports that the cooling sucked.
I wouldn't be surprised (Like people have said earlier) that the iMac will generally be better at cooling anyway.
1. Thunderbolt GPUs don't exist yet. Or rather, ones as powerful as a mid-range graphics card don't exist yet. Thunderbolt only outputs the bandwidth of a PCIe 4x slot; discrete video cards use 8x and 16x. You'd get no real benefit from a Thunderbolt GPU at this point.
2. The 21.5" iMac's cooling will likely improve, while the 27" iMac's cooling will likely worsen. To compare them to a retina is literally comparing apples and oranges; a retina MacBook Pro still uses the same CPUs and GPUs found in its non-retina counter-part, so an increased degree of heat is not surprising.
If you guys don't want it so hot, don't want it so thin.
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For comparison's sake I have correlated imac and mbp. Notice the large capacitors on the imac, cant see if they are solid capacitors or not? They are the white dots across the board, notice the mbp uses a diffident type as the solid cap's normally stick up by 10mm or so. This is one of the advantages of having a bigger package, it also makes it cheaper
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