Keep the 750W PSU and go with a GTX 770 or 780.
AMD may look better from a specifications-per-dollar standpoint compared to Nvidia but Nvidia offers superior calculations-per-watt performance.
You don't need double precision compute in a gpu for gaming, or most things. The true measure of calculation prowess for gaming is game framerates, and sorry to burst your bubble but that's the metric in which the 290 wins hands down. It's faster than the 780 in the case of most games for $100 less
Most AMD cards are loud, hot, and inefficient compared to their Nvidia counterpart.
Wrong. Maybe in previous generations, but not for this generation, and definitely not for the sapphire branded 290 (which is both very quiet and very cool). I wish people would stop regurgitating the same misinformation
Edit:
See, I've noticed that AMD optimization on a lot of games is pretty stuffty sometimes, so I was going to go with nvidia just to enjoy that aspect. Thanks for pushing me over the edge.
we've had this discussion in this thread before
I don't think that's true. The only modern games with a measurable difference that I know of are watch dogs and apparently blockland w/ shaders. Aka games that were poorly optimized in the first place, so I don't agree with a general blanket statement like that. I'm not necessarily trying to dissuade you from the 780 because it's a good card, but it's important to know the facts before you make a major purchase.
If there's more games than these two that are poorly optimized for amd would you mind sharing them? It would be very helpful to know