Biostar TB250-BTC PRO - 12 pcie slots
ASrock H110 Pro BTC+ - 13 pcie slots
and now the ASUS B250 Expert Mining 19 pcie slots
I will say it can be a pain in the ass to track down issues with that many GPUs.
How do you get 12 GPUs in a rig? What board has 12 slots?
Other than saving the cost of a MB, HD, mem,psu and CPU ($350 what advantages do you get from a 12 cpu rig versus a 6 gpu rig?