No word yet of possible fix for micro stutter with triple monitors. I would go with sli GTX770 or 780, the 780ti is too expensive for the performance boost I think and 2 780s should perform really well.
If you have the money and really need the performance I would go with the SLI 780ti just make sure what ever setup you go with that they have at least 3GB of RAM.
Due to AMD drivers and the crazy amount of heat the 290x produces I can't recommend it for crossfire right now.
Thanks for your reply
I have used 2xR7870hawk and 2x MATRIX HD7970 Platinum...they are all AMD cards.
Maybe I should have a try on Nvidia cards next time..AMD is just pushing their ultimate fans to the opposite.......
should I sell my 7970s and pay 150$ more to buy 770/680 4GB SLI or Single 780ti?(I'm worrying maybe 3GB is not enough......)