Asus raise their motherboard mining game with their Asus B250 Mining Expert Motherboard successor with 19 PCI-E Slots. This new mining motherboard is called Asus H370 Mining Master and comes with support for up to 20 GPUs using PCIe directly via USB connection.
The presence of a direct USB connector mounted on the motherboard simplifies connectivity by allowing the riser USB cable directly into the PCB and the direct connection is stronger than using a PCIe card, with less chance of accidental disconnection, as well as reducing the total number of parts on your rig.
I'm interested in getting one of these. I run Windows currently and this will give me a reason to brush up on Linux. Or maybe I'll just get EthOS.