I think an easy way is the frequency, after flashing to 6970 i believe it should run at the 6970 speed of 880mhz instead of 800mhz in a 6950.
according to http://forums.guru3d.com/showthread.php?t=350307,
he states that YOU have to manually set the clocks using sapphire trixx, problem is every time I do this, when I reboot, my clock go back to 6950 stock clocks, even after I have set a profile and clicked on the START WITH WINDOWS option. I even disabled CCC at startup and I have downloaded 3 different version of SAPPHIRE Trixx. All do the same