With the introduction of the 7000 Series AMD cards and the 600 series NVIDIA cards, there is little to no point in investing towards a GTX 500 series. As displayed in the benchmarks above, the 670 clearly wipes the floor with the 580. And when you couple that with the newer 28nm Kepler architecture which yields better OC'ing performances due to lower temps and lower power consumption WHILST increasing performance, the decision is boils down to common sense.