I prefer Nvidia to ATI because of Physx, better AA (for example GTS 450 owns HD 5750/5770 on it) and 3D vision in low/mid range GPUs.
In another pc I owned an HD 5670 which I immediatly replaced with a GTS 450 because it had a lot of drivers
/pci express issues.
In my experience, ATI cards are better of same-range Nvidia cards only in AGP versions.
So I want to buy a Nvidia card for this pc if possible.
I'm looking to save money to get the GTX 690... or is better to get 2 GTX 680 in SLI?
I want to play heavy 3D games at max settings @1920x1080 (i'm looking for a single super-widescreen monitor too) at full framerate... I'm sure that both HD 7970 and GTX 680 will do it right, but i use a lot physic accelleration in games, so i prefer Nvidia cards.
The GPU will work with a Core i7 3770k (or with an AMD FX 8150 or with a 6-core [12 threads] i7), and 8GB DDR3 @2400MHz RAM.
For the Core i7 3770k i chose an ASUS asus p8z77-v DELUXE motherboard (which supports SLI/Crossfire and PCI Express 3.0)