We can confirm that the RMA (Return Merchandise Authorisation) rate is much higher on the overclocked boards than it is on the non-overclocked 7900 GT cards. We asked around among the vendors and learned that only the vendors who pushed their cards to the limits have the massive RMA problems. The more conservative companies that might have overclocked 7900 GT a bit don't appear to be suffering from such high RMA rates.
It is all about the aggressive overclock of the poor G71GT chips. In essence, all you need to do is to lower the clock frequency and you will be fine. But then you may be a bit miffed that you bought an overclocked card in the first place.
The other thing that you have to bear in mind is that 7900 GT is a single-slot cooler card and it is not omnipotent, it cannot take the all heat in the world. ยต