if i slid with 2 gb is that bad
It's not bad at all but I would go with a single GTX 670 for BF3 and then SLI later if you want to. When you SLI or X-fire you can run into some minor tearing/stuttering issues. Some people it really bothers while others hardly notice it. Some games run good with SLI and X-fire while others are just ok and some games you can't even run while in SLI/X-fire.