Like anything it will depend on the adapter. Still though, your computer should at least "Detect" the 3rd monitor even if it won't let you set it up as an Eyefinity span.
The 3rd monitor is not even listed in CCC? If not then it's either a cable issue, or it's at least possible that the DP port on your card is dead. Does your card have a 2nd Mini DP port? And if so have you tried it instead? Otherwise, your DVI cable, or your adapater is hosed. Or the monitor is hosed. Does your monitor support any other inputs than DVI? Like HDMI which would still allow you to do Eyefinity via adapter?
i7 3930k w/Corsiar H100i
Gigabyte X79-UP4 Motherboard
Creative SB Recon3D
2x 128GB Kingston SSDNow! SATA III in RAID 0
2x Sapphire R9 290x in Crossfire
Antec TruPower 1000w PSU
LG Blu Ray Burner
Corsair Vengeance 16GB DDR3 1600
Cooler Master HAF 932