Looking for a better GPU for my CPU. I don't have a budget, however I don't want bleeding edge. My benchmark is being able to play games like Metro: Last Light between medium to high settings. I have a Core i7 920, overclocked to 3.74 GHz and my current GPU is a GTX 260, slightly overclocked. I have a Corsair TX650w
For your CPU and PSU you should get the GTX 580. Generally you will need a card at least 3 tiers higher than your GTX 260. Your OCed CPU will not bottleneck a GTX 590 or HD 6990 but you will need to check if your PSU can handle them.