Depends of what you mean by overkill. If you mean will they be bottlenecked by the i5, then no, neither will bottleneck the i5. If you mean overkill for the games you play? One could argue that point (I wouldn't, but I'm sure someone would try). So either way no, not overkill.
That's great, I will definitely go for the 7970 Ghz edition then.
But I have also heard many games have driver issue with AMD GPU, is that true?