how to know sli combatable video card chipset ?
i want to but gtx 650 ti boost sc 2gb with a normal gtx 660
Nope you cant. With nVidia, the gpu's need to be identical (with a few exceptions 9800GTX, 9800GTX+ and GTS250 but only in certain cases)
they also need to have the same memory amount as well.. so its best to get the identical cards.
AMD can do crossfire with some different models working together...