Have a Sapphire HD7970 Vapor-X GHz Edition(3GB, HYNIX AFR memory)
Stock bios was giving ~52sol/s (1050/1500)
Tried GIGABYTE 7970 with HYNIX AFR Memory, OS started but mining failed(0.0 sol/s)
After that flashed ASUS R9 280X with HYNIX AFR memory.
And now my GPU gives ~83-87sol/s, peaking at 96sol/s in Claymore's v4.0
http://i.imgur.com/ZW9NIdd.jpg?1