I've been on 3x 670 4gb cards since early 2012...they've been great for my 28" surround setup...mostly. Some obvious lagging and stuttering and turning down this and that trying to make it run better in games like Bf4, GtaV. Decided it was time.. I ordered 3x EVGA 06G-P4-4995-KR 980 Ti's..2 for me, 1 for my brother. WOW.. all I can say. Never thought I'd see games run so smooth at 5760 x 1200. Only tested Gtav and Bf4 so far, but those are some of the most taxing, so other than maybe Crysis 3 which I'll be running later I doubt I'll be disappointed.
Only complaint if any is that I got no game codes. Wanted to order from Newegg.com to order on my newegg account, but with the lack of stock and limit of 1, a rushed out game wasn't worth the wait, I.m.o. I found this link
http://forums.evga.com/Watercooled-EVGA-GTX980Ti-SC-ACX-20-SLI-m2355179.aspx to use Ek block and stock Evga backplate, but after having the sweet lights on the 670 XSPC blocks I'm holding out to see if they will release a block for the Ti. Temps on air in game are 69c max on top card, 58c max on bottom card, fan speed around 80-90%, acceptable enough to wait on XSPC!
I never wait this long to upgrade gpu's, but I was saving for my first home until last year. I almost upgraded to 970's because the price / performance and fact the XSPC 670 blocks were compatible seemed sweet. But I couldn't justify the cost at the time. The 980 Ti's were a no brainer after seeing all the reviews!
Firestrike with 3 x 670's clocked to 1200 on the core =14198
Firestrike extreme with the same clocks = 7740
Firestrike with 2 x 980 Ti's, stock clocks that boost to 1278 =21342
Firestrike extreme with the same clocks = 13842
More importantly than benchmarks is the smoothness of Bf4 and GtaV.. ALL settings maxed in both games, they run and look amazing!!