I am currently planning a similar build! I was looking, for GPU's, at the GTX 670 FTW edition ones. They provide an almost-eeriely similar performance to that of their more expensive (around a hundred $$ more) brother, the GTX 680. I haven't look much into Radeon graphics cards, but I hear that their Sapphire 7970's are pretty comparable for only about $400 (Newegg also gives three free games along with it). For CPU's, I would consider the i7 3770k and the i5 3570k. They both run great (from what I hear) for their price. As for mobo's, I was considering the Asus Sabertooth Z77, because a lot of it's features but am now looking at the Maximus V Formula... Republic Of Gamers endorsed. The BEST GPU on the market (or at least, most expensive) is the GTX TITAN. It's around a grand, but hey, if you want to play Crysis 3 on three 1080p screens with extremely high settings (not sure if Ultra will work) with over 30fps, then that's your baby.
(I'm just a consumer, not an expert btw).