From what I've heard, you CAN run xfire on an sli board (and vice versa) but it requires a software hack, I haven't looked into the specifics I've just heard its possible. If you dont want to mess with that, then going with nvidia might be a safer bet. As for ram, I'm pretty sure if you make sure the pins match (i think its pretty standard 240 now for ddr3) and make sure the ram is designed for the type of proc you're using (intel), you should be fine. Especially if other people are using the same board and ram lol.