Yep same issue with my cards i can only get the too 1050 and i have games crash on me as soon as they load i want to use voltage to stop this from happening but its locked ..
Grr i really only got the HD7970 so i could over clock as i have seen almost everyone take them too 1200 mhz with no issues ..
I called and asked, they said that it was locked due to people calling in with overvoltage issues. I replied by saying that we should have the freedom of doing whatever we want with the card, and we're the ones risking our money to boost the potential of the card, not them. But nothing really changed.