Curiously, I'm not concerned about the bug you have with vsync ON, from a game to another, Vsync experience is inconsistent, but the choppyness you experience while vsync's off.
Could you please provide more details on your configuration? Did you overclock the card?
Using non GHZ 7970 cards from Sapphire and Gigabyte and I experience no issues, no frame skip with or without vsync.
What I do get though is flickering in Assassins Creed Black flag menus when CFX is enabled.
Gameplay is smooth in Black Flag, Cryssis 3, BF4, Borderlands2, Tomb Raider, Bioshock Infinite and older titles.
Also, did you make sure to completly uterly erase any Nvidia driver data from your set-up?
Making snowman out of rain