I'm sorry but it's really not anything like the car has less Valves.... Comparing to the GTX980 it's more like the 980 is a car which is advertised to be able to drive @300kmh whihe the 970 is a car advertised to run @270kmh.
The actual problem is that while the 980 car drives absolutely fine @300 kmh, the 970 car is juddering violently and starts braking from time to time at it's advertised 270kmh... I wouldn't like to drive a car like that... Better limit it to what it's capable of 24x7... e.g. a nice, safe and sufficient 260kmh.
So... no, it's not just a wrong spec on a piece of paper, the actual performance suffers...