Mephic :
Better to buy one strong card than two weaker even if they give better performance SLI and CF has too many drawbacks. All this stuttering and driver compatibility stuff is a nightmare. Still SLI works better than CF.
I dont not agree. There are not loads of problems with SLI as many belive, it works quit good.
On the net all you hear about are those with the problems not the 80% that it works good with.
If as you say, buy the strongest singel GPU that would be the 680 from nvidia and 7970 from amd.
As 690 is duel core and Titan is just a waist of money unless you got multimonitor setup.
And buying the strongest nvidia 680 is just dumb, as it costs a lot more than it taists.
The 670 or 7970 would be the best. And as he wants more power, not more vram from titan.
SLi CF would be the best choice.