Two things I've seen reported to clear this issue. I think I've thrown everything but the kitchen sink at this DX REMOVED business and these two things are the two that have stuck (first came from another user)... as odd as they are... people have reported it helping or fixing. On the flip side of this coin... I OC the ever loving snot out of my 480's and never had this issue (I do use frame limiter but even without it, nope).
1) Underclock your GPU slightly (with afterburner) DO NOT use the RiviaTuner overlay program that comes with it. Overlay programs do not play nice with Origin in Game.
2) Frame limiter
Open Notepad.
Copy and Paste this:
GameTime.MaxVariableFps 60
Save it as "user.cfg"
You cannot have user.cfg.txt
enable "View Extentions of Known File Types" from Folder Options in Control Panel
Put it in your PvZ directory
\\Origin Games\Plants vs Zombies Garden Warfare
