The Current SFF (Small Form Factor) Market and Trends:
As I mentioned in a previous post, I had suspended work on my iMac G4 20" upgrade until Small Form Factor Ivy Bridge Boards become available. I have become somewhat of a small form factor enthusiast as a result of these projects and am excited by the accessibility of what previously were industrial only form factors as well as new specifically targeted enthusiast boards such as the Raspberry Pi, Android Compatible ARM boards, and Intel's NUC line. I am pleased to report that I am in possession of one SFF Ivy Bridge Board and have another two ordered and en route.
As the size and power consumption of powerful processors and boards continue to decrease these mods will only continue to get easier, more diverse, more powerful, and less expensive. The one "nuisance" of the recent computing era (at least for these projects) has been an unbalanced focus on shrinking things primarily by thickness. The ultrabook and tablet markets have caused a "flattening" of components without as significant a change in the other dimensions. Take the Mac Mini for example, the overall volume decreased as a result of a dramatic reduction in height, but this was in spite of an actual increase in the footprint (length x width).
 |
| Old on top, New on bottom Courtesy of CNET |
SFF Computing and iMac G4 Mods
 |
| A Tight Squeeze |
To sum up, the original iMac was convection cooled were physical contact via heat pipes carried heat to the top of the dome where a fan blew out. Thus the very poorly ventilated case was designed to be cooled with room temperature air coming in through slits at the bottom of the dome and hot air being blown out through the top of the dome. Any air cooled motherboard/cpu (by far the hottest and most important component) benefits from being as close to the top as possible because it decreases the distance the heated air has to travel before it reaches the case fan and ventilation and decreases the heat of the overall dome and the heat the components above the mono/cpu are subjected to. Also, probably most important, placement at the bottom of the dome will unavoidably result in poor, obstructed ventilation. Any other component, especially wiring, will have to go above the CPU and mobo. As the dome tapers to the fan at its apex and the faraday (metal inside) cage makes most of the periphery of the dome difficult to use for components. If all you want is a motherboard and cpu, it can be done with a large heatsink to the top of the dome and a low thermal output processor, but no other components could be added and wiring would still be difficult.
Using a small form factor board allowed me to use a Core i processor at the top of the dome and allowed the rest of the dome to be used for a pico PSU, a full 5.25" optical drive, and a 2.5" solid state HDD. As the widest point base still barely fits a mini itx (and port blocking is a problem), so options have been limited. I am fairly certain the the mac mini will eventually shrink in all directions and that it will be suitable for a G4 mod. In addition, I am hopeful, new form factors of computing will emerge and we will see other alternatives to the ultrathin rectangles that dominate today. But for now, this is what I am working with:
Current Ivy Bridge SFF Options:
I will be reviewing each of the options based on features, cost to performance ratio, size and workability with the iMac G4 mod, and "hackintoshability". Therefore, expect this post to be a work in progress with periodic updates. Again, I am focusing on high performance x86 architecture, but this is by no means a slight to alternatives such as low-power Nano/Pico x86 boards or increasingly popular ARM devices, this is simply a matter of personal preference.
Choice 0: Quanmaxx KEEX-6100 ECX board
 |
| KEEX-6100 with large heatsink |
I am listing this as "Choice 0" because it is based on Sandy Bridge Architecture, but it has been overwhelming successful particularly as a hackintosh running OSX Lion. It is available from Quanmaxx's USA store and is even available in a wide temperature variant. Here it is seen with an extra large heatsink I adapted when I upgraded this to a Core-i7 Quad.
Choice 1: Avalue's EPI-QM-77
 |
| Front View |
Though this EPIC board is slightly larger, this board is"thinner" as a result of more room for ports on the edges, thus no need for the stacked ports seen on the ECX boards. It remains a small form factor that easily fits the iMac G4 chassis. It is available from Global American and I have it in my possession and just started working with it.
 |
| Back View |
 |
| From Left to Right: Mini itx, EPIC, ECX |
 |
| From Left to Right: Mini itx, EPIC, ECX |
Choice 2: Aaeon's GENE-HM76 ECX
Also available as a more expensive QM77 (has extra corporate features, most apple mobile Ivy bridge processors are HM77 (very similar to HM76).
 |
| Courtesy of Aaeon |
This is a true ECX board and identical in size to the Quanmaxx ECX. I have purchased this board from NextWarehouse and it is en route.
Choice 3: Intel NUC: DC321BY QS77
 |
| Courtesy of Newegg |
Although it only contains a Core i3, this is the one I am most excited about. This is because of reasons outlined in my previous post. This is the smallest Core i board that intel believes is possible. This board is targeted at the mainstream and this model includes thunderbolt connectivity. This comes with a "chassis" and is likely to see upgraded models at regular intervals in the future. It is widely available from vendors including Newegg. It has been ordered and I will continue to update as I learn more.
