Originally Posted by
MindCrime
Those cards are going to be crazy hot unless they're liquid cooled.
Besides the heat you've got two limiting factors, physical connections and pcie lanes the chipset supports. z77 has only 8 lanes, not a good choice. 990fx has like 38 and x79 x99 have 40.
If i recall the tahitis are 250w cards, and can go north of 85c. You're going to need at least a 1200w PSU. I think it would be cheaper to put them into 2,3, or even 4 different rigs. Also I believe a lot of motherboards like extra juice when running extra gpus so make sure you use one with the extra pcie power. And again, if they are nearly touching eachother they'll be temp restricted under heavy loads.