It is possible, and definately viable with a dual x8 pci-e configuration, but for the ultimate gaming performance, I would choose x99, as it allows the 980s to have x16 pci-e lanes, unleashing a little extra performance
So wait. I want to do an x99 chip (the five hundred dollar one) with the maximus 7 formula however can I run it with dual 980s?
You will have to buy an x99 motherboard, and an intel core i7 extreme cpu (as well as ddr4 ram). I would reccommend the 5930K CPU, as it allows you to run both the cards at x16 bandwidth