قطعاً دوتا 770 قوی تر هستن
من جواب یکی از کاربران فروم tomshardware رو هم نقل میکنم:
I'm not sure if the 780ti can support 3 monitors although it should. SLI, although not very buggy, its still not as good as one card reliability wise. Some games wont utilize SLI as well. Therefor you wont get the full performance of both cards. I would go for the 780Ti. One card, almost as strong as 770's SLI. Less issues and games will utilize the whole card. Plus it is just easier to manage. I was going for 770 SLI but with the new 780Ti, im just going to get that instead.
Either way would work fine. Although I think a single 780Ti will perform better than 2 770's when it comes to games utilizing multi-gpu support. If you did 770's I would go for the 4GB version since your running 3 monitors all in 1080p.
Also in the future you could get another 780Ti, which wouldn't be for a long ass time tbh.