Oh yeah, I'm having some trouble with finding a power supply that'll be good enough for the GTX 760, but I'm sure I'll be able to get a better one for the better card. GPUBoss doesn't appear to list power needs for the cards. :/
Don't use gpuboss, or any site like it (hwcompare, cpuboss, etc.)
All they do is compare on-paper specs and then give it an arbitrary rating. Comparing things like clockspeed is goddamn asinine, and I really hate those sites because of it.
For a 760, you'll probably want 500W or so. You could go lower, but they're usually the same price as the 500W psus.