I am considering to do SLI, and now i currently have a graphic card which is the asus Gtx 670 Direct CU II 2GB and my doubt is:
Could i get other brand cards to SLI with this cards? if not Could i get GTX 670 Direct CU II TOP to SLI?or could i get the Asus gtx 670 Direct CUII 4GB or should be the same card with the same charecteristics?
They can be of different manufacturer but if you get one with 4gb VRAM and your current only has 2gb you will not be able to access that extra 2gb VRAM. Also, they will clock down to the speed of the slowest card. Either sell your current 670 and buy 2 4gb 670's or just get another one of the same one (this is what I would do, the ASUS is a good brand and the VRAM won't help you unless you are going multi-monitor).