New Motherboard for 6-8 GPU

Hi All,

I'm looking to purchase a motherboard for 6 GPUs (980 TI's) and possibly grow to 8 later. It will be in an open air case with 1-2 1500W PSU's. I will be using PCIe riser cards to connect them of course. Any recommendations for an Intel i-series (or xeon) motherboard?

Thanks!