As of right now, I have an EVGA GTX-690 and I am not too blown away by the performance. I am trying to decide between getting another 690 or ditching the one I have and going with 2 Titans? Here are my questions. with 2 690s or 2 titans, will I be bottlenecking myself with an i7-3770? and will my 850w power supply suffice? or will I need to upgrade that as well?
If you are oc'ing your cpu (or anything else) I would suggest a slightly larger wattage PSU than what is recommended (and make sure it is a quality PSU from a reputable manufacturer such as Seasonic, XFX, Corsair, etc.). I can't say for sure, but I don't think your current CPU would bottleneck either SLI set-up.
Two 690s is a Quad-SLI, not the most optimal setup due to compatibility in games and performance scaling, especially considering that there is only 2GB per GPU. I would go with two TITANS or, even better, 3x780s (if your motherboard supports tri-SLI and you'll need 1200W PSU). What resolution are you using for games?