The problem isn't necessarily just on your side. The game is horribly built on PC, so no amount of tweaking or settings changes may make a huge difference.
I think this is one thing that Bioware is going to have to step in and fix. I refuse to play the game right now as its badly marring my enjoyment, even without all the other stuff that needs addressing.
All this being said, though, i was pretty surprised by the lack of quality difference between low preset and ultra preset in this video i found:
https://www.youtube.com/watch?v=Q70DxlW0nb0
I was shocked to find out that between the 2, at least in that video, the game is like 90% the exact same.
