HD7970 ( Tahiti XT )
Core's 2048 operate at 1GHz clock
3GB of GDDR5 memory at 5.5GHz
Memory Bandwidth 264GB/s
Memory Bus Width 384-bits
Texture Units 128
ROPs 64
Manufacturing Process TSMC 28nm
Price $449
HD7950 ( Tahiti Pro )
Core's 1920 operate at 900MHz clock
3GB of GDDR5 memory at 5.0GHz
Memory Bandwidth 240GB/s
Memory Bus Width 384-bits
Texture Units 120
ROPs 60
Manufacturing Process TSMC 28nm
Price $349
HD7990 ( New Zealand ) HD7970 X2 Double all specs "March Realease"
6GB of GDDR5 memory at 5.5GHz
Price $699.
For Comparison's sake here's last gens specs
HD6970
Core's 1536 operate at 880MHz clock
2GB of GDDR5 memory at 5.5GHz
Memory Bandwidth 176GB/s
Memory Bus Width 256-bits
Texture Units 96
ROPs 32
Manufacturing Process TSMC 40nm
Price $369 ( on release )