I had calculated the efficency from the official TDP Value on wikipedia and the max. Hashing  values of the Litecoin wiki.
The 7970 and the 7950 are identical efficent in theory.Why do you rate the difference as "nowhere near"?
Any examples or experiences? (So far i tested 7970, 5970 and 6870)

I recognised that some manufatures are better than others.
so i gett only 710khash out of the possible 800khash.