You're not going to fix hiccups running at 5760x1080, most games aren't designed to run in that high of res, I have a feeling you're going to buy yourself a new card for nearly $300 and have the same exact problems because they're coding errors rather than hardware errors....
Edit:
Sapphire is a good brand, they're the company that makes the actual card circuit boards for a lot of the other manufacturers, they ship them to XFX and MSI, and those guys just put their custom fancy heat sink on them. I used sapphire back in the day when I used ATI cards.