I also run my two connectors on separate rails on my Antec Neo HE550.
I have my eye on the Corsair 850 Modular when my Antec gets too "pap in die broek" .
Phatta, you can play with all the settings all you want...just ALWAYS run shadows LOW and HBAO off.
^ That takes about 20% performance away when running max.
Cene has also seen waaay better FPS with those off.
I'd rather get that extra 20% than have dips to 45/50 FPS.
I average 65 - 175 FPS with BLOOM off / HBAO off / Shadows LOW / 4xAA / 4xAF (avg 114 as per Fraps benchmark) :

Chopper down!! Bahaha