If you're hellbent on getting a new GPU right now, then go with a 780 ti, or even 2 780's. I can tell you that a single 780 is a lot of GPU @ 1080p.
What monitor do you have?
ASUS DirectCU II ($709 Newegg)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121838
EVGA is a great brand too, though a little more costly.
***When you say money isn't a problem, that leaves open a lot of room for interpretation. You should really post you're intended budget, even if it's I don't mind spending up to $6,000 =D. I mean, the Titian Z is coming out at $3,000... Maybe not worth it, but still.
****If you want a more silent rig, and better control over your GPU fans, then you want a proper water cooling set up. I mean, any GPU is going to be loud as hell if you kick the stock fans up to 100% or something.