I'm quite new to technical stuff.
Can anyone answer this question?
Can you have dual GTX 670?
If so, how ?
You need to go do some research if you have to ask this question. Spend some time on Wikipedia, the forums here at Tom's, and in general do some Googling. I'm not trying to be rude at all, but we can't give you a Computer Science 101 course here. Well we could but I'd want to get paid.
And you want to research with keyword: SLI