I think 2.4.6 introduced support for new R9 cards.
M7H / Matrix 7970 P (flashed to R9 280x Matrix P) + 2 x DELL U2713HM / i7 4790k + h100i push&pull / 3 x Kingston 3k SSD 120GB / 1 x Corsair ForceGT 120GB / TridentX 2400 2x8gb / Corsair Graphite 600t case + AX1200i + NZXT IU01 + Bitfenix USB3.0 internal adapter