I read the faq and from what I read there are some cards that can sli or crossfire with each other even if they are not in the same series. I bought a GTX 660TI 2GB OC, am I able to sli with another card or do I have to use the exact same one again. And lastly it says triple sli ready, does that mean I can use 3 cards in sli?
You can crossfire two radeon card from same series ie 7970+7950 is possible but not 7970+7870.
For nvidia it is not possible to sli two different cards. Although same card from two different vendor should be OK.
Yes you can sli three of them.