I'm between the Gigabyte NVIDIA GT 640 1GB DDR5 or the EVGA NVIDIA GTX 750 2GB SC, clearly the 750 is better, but my processor is an Intel Core 2 Duo E6700 (2.66 GHz), so I don't want to waste my money in a card that I won't use fully (750) due to bottleneck problems, Which of them should I buy? (Or if you have any other suggestion, I'm searching for 60W approximately power consuming cards, I can't upgrade my processor is the best one that my MoBo admits :/)