after some researching, the GTX 660 Ti is out, i don't like the 192bit memory bandwidth on it, HD 7950 is not clear choice yet, i discovered the Tahiti based HD 7870 LE which runs almost as good as the HD HD7950 but it has higher power consumption than HD7950.
i dont know if i should go for the cheaper HD 7870 le with higher power consumption or the more expensive but lower power consuming HD 7950.
edit: My motherboard only supports crossfire so another minus for GTX 660 Ti