What Graphics Card to Get?

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1

I already have a pc built basically but some changes in plans caused me to have to delay my graphics card by a few months. So I have a f2a85-v pro motherboard, a a8 5600k APU, 8GB ram, 700wat PSU, and a 2TB mechanical hard drive. When I started looking for graphics cards the HD radeon 7970 direct CU from Asus looked good, but I just want to get more opinions. my price range is 350-450$ and i'll mostly be using it for gaming. I have a ton of games but I want to start gaming on my primary OS, Ubuntu 13.10. I hear that Nvidia cards have better openGL support but I'm also curious about the potential of Mantle. 

So basically I want to know what graphics card is best for gaming with on linux within my price range. And whether in general AMD or Nvidia is better for this.

2

I think a 7970 will be bottlenecked quite a bit by a 5600k, i think the most you could push on that CPU is like a 7870 and it would probably be better to try and overclock the CPU a little bit too

3

The most you can push with that CPU is any pci-e card. How much bottleneck you'll get really depends on clockspeed for that CPU.

Nvidia cards had better openGL support like 6-7 years ago. They are the worst cards to get for linux and will be unless they go open source with drivers. I suggest using windows for gaming, the drivers are more mature. OpenGL might be faster in linux but it depends on the game (very few "popular" games run on linux).

Any R9-280x is good.