Best Video Card for this System?

So I am building my first PC and am debating which GPU to buy. The rest of this system is pretty much concrete, but need a GPU suggestion. Here are my system specs and why I chose them:

Intel Core i5-3570k this CPU is a monster. Since I am gaming with a small amount of non-CPU intensive editing programs, I chose this bad boy. To get a reasonable performance increase, I would have to go up to the 3930k, which is another 300 bucks. Since I am overclocking, it is hard to beat a 4.5 GhZ i5...

RAM: G.Skill Ripjaws 8 GB @2133 MhZ So first off, this RAM is similarly priced to 1600 MhZ Vengeance by Corsair. This is the bomb dot com, and I might be able to push this stuff to 2400 MhZ.

Motherboard: AsRock Extreme 4 Z77 I can overclock my 3570k, get RAM up to 2400, the whole 9 yards.

GPU: Don't need CUDA, your guys' suggestion for the best gaming card for about $300-400.

CPU Cooler: Zigmatek Dark Knight Night Hawk Edition. This cooler is only about a degree hotter running a 4.5 GhZ i5, and half the price. Would I be getting a reasonable upgrade with the x60/H110?

Storage: Samsung 840 256 GB SSD & 3 TB Seagate Barricuda

Case: Corsair Carbide 200R: Best case for $60.

Optical Drive: External DVD Writer

OS: Ubuntu 12.10 (Steam, Spotify, Minecraft, and Chrome are usable on it)


Go with a 7970


7950 or 7970


7970 for gaming, 680 for editing. Also, please use next time :)

Looks like a 7970 is the favorite in this group! Thanks (: