I have a GTX 570 and I've have screen tearing ever since I put the machine together a few months ago. I have it in games, netflix, pretty much everything (it's worst and most visible in Ungine's Heaven). Not all the time, but very frequently. It also stutters when I watch something with a reasonable amount of movement. Even with V-Sync enabled.
I have a powerful enough machine (i7 2600k, 16GB of RAM). Any thoughts on what's happening? Could it be a bad card? I have a dual monitor setup, if that helps.
I know this is an older post, but I've been fighting this problem on my 670 FTW. I just "fixed" it after playing with settings in game and with the card I ended up simply selecting DX9 to get rid of the screen tearing. Not too savvy on the benefits of DX11 or DX9, but I hope this helps your issue somehow. Yours sounded a bit more involved than mine.