I suddenly got the opportunity to change the two GTX-470 on my Gigabyte GA-890FXA-UD5/PhenomII-1075T with two faster cards, while sticking to gaming hardware for CUDA number crunching (molecular dynamics). Considering the limits of the motherboard (North bridge AMD890FX, South bridge AMD SB850, 2-Way/3-Way ATI CrossFireX), is GTX-580 the fastest card that could replace GTX-470? Thanks for advice francesco pietra