Won't work. AFAIK there is no housing available that supports more than 4x graphic cards (power, cooling, ). Technology is not there yet to really replace internal graphic cards beyond a certain performance level simply by slapping them into an external housing hooked onto a Thunderbolt port.
Recommended components are listed on
tonymacx86.com.
My hackintosh consists of a Gigabyte H77 mATX board, a 3770 i7-CPU @3.4GHz, 8GB Ram, 120GB Samsung 830SSD, a cheap FireWire card with FW400 ports, an old Bluetooth USB stick i had laying around and an older 6850 graphic card (mostly for power consumption reasons, as i recycled an existing housing). It has cost me ~60-70% of what a mini server would have cost me. If i would have gone with 1:1 comparable components performancewise, cost would have been even less.
For the remaining cost difference to the mini i could have purchased quality components like case, PSU, Bluetooth and Wireless and would even have more room (e.g. for drives and a graphic card of my choice), not to mention the far superior performance of the DIY build (CPU, SATA-6G, graphic card, USB3). I consider the missing Thunderbolt interface a merely academic issue, as USB3 boxes usually are far cheaper and available in much more flavours than the few pathetic and overpriced Thunderbolt devices. And even then i think Thunderbolt-equipped motherboards suitable for a hackintosh are already announced (if not available by now).
Granted - the mini as a package (small, power-efficient and silent when not under load) is hard to beat, but as soon as you think out of the box on one aspect or the other it's very easy to do.
Don't get me wrong - i do own several Mac products and i'd really have preferred to get a suitable replacement machine for my old MacPro, where i don't need to worry about whether the OS update may break it (which it still could on a "true" Mac, though then it usually is not my job to correct it), but in the desktop segment imho Apple currently is not competitive anymore by any means for any product in their portfolio!