I've got Nvidia GeForce GTX 560 Ti 1GB and I was planning to get another better graphics card with at least 2 GB but why should i? I heard that you can use two graphics card at once sooo ... Can I just buy another GTX 560 and just kinda ... "plug" it in?
So, if I want a better graphic card (2gb) I need a new motherboard?
No, your board only supports Crossfire which is ATI, you need a board that supports SLI. And if you use a 2 gb card with a 1 gb the 2 gb card will only use 1 gb, same goes with clock speeds if that makes sense.