12.8 = august 2012.... so yes. 7xxx cards where already out at that time...
Why don't you at least try 13.4? They release later drivers for a reason.
There is also a good AMD removal tool on their site to clear old drivers. I suggest you run that before installing updated drivers to eliminate any other issues.
well i use AMD-APP-SDK-v2.7-lnx32.tar on my 7870...