The Press shots of HD 7950 suggests that it will not be sharing a common
design with its bigger brother HD 7970. It will also use a separate PCB design than HD 7970, eliminating any chance of being unlock able to HD 7970.
Unlike HD 7970 colling assembly, which pushes hot air out of the case, the reference HD 7950 design uses a cost-effective heatsink with internal ventilation using a top-flow fan. HD 7950 ref. pictures 

AMD Radeon HD 7950 Specifications
Technology 28 nm
Shaders 1792
TMU 112
ROP 32
Bus Width 256 bit
Core clock 800 MHz
Memory Clock 1.25Ghz
Pixel Rate 25.6 GPixel/s
Texel Rate 89.6 GTexel/s