Wait! I just found something that might be better:
http://www.silverstonetek.com/product.php?pid=488- Stackable
- ATX
- 12.2 inch gpus
- fans included (well they´re probably weak but at least they already thought about a cooling solution / air flow...)
Right now I´m investigating further... (how many gpus will fit etc...)
Only a board like the Biostar GT7 which has 4 physical slots could work in a case like this. And this case has 7 PCIe slots so a maximum of 3 cards. You need something with 8+ slots. And dont worry about stackable.
lol .. no. Tyan case and mobo , 8 GPU just fine.