Crossfire 6950 or R9 280x?

[shadoweliterecon]

I have been debating an upgrade for my computer in order to make it more capable for BF4, and I've decided to do one of two things.
Buy a used 6950 and crossfire it with my existing one
OR
Buy a brand new R9 280x
My question is, which would yield the highest performance increase, and by how much? Also, is my system even capable of supporting crossfired 6950s?
Existing parts:
MB: http://www.newegg.com/Product/Product.aspx?Item=N82E16813131733
HD: http://www.newegg.com/Product/Product.aspx?Item=N82E16822145532
RAM: http://www.newegg.com/Product/Product.aspx?Item=N82E16820231455
CPU: http://www.newegg.com/Product/Product.aspx?Item=N82E16819103996
Case: http://www.newegg.com/Product/Product.aspx?Item=N82E16811147153
PSU: http://www.newegg.com/Product/Product.aspx?Item=N82E16817371031
GPU: http://www.newegg.com/Product/Product.aspx?Item=N82E16814161372
Thank you for your answers!

 

[theDoItYourselfAmeture]

can you redo your links, its taking me to the newegg homepage for some reason?

 

[Stealth117]

I'd go with a R9 280x. For one it runs cooler and consumes less power. The 6950 doesn't farewell in BF4. A R9 280x would yield the highest performance increase at least if your going to play on ultra @ 1080 with AA .

BF4 Benchmark

 

[shadoweliterecon]

Thanks for the replies so far, I appreciate it. Keep them coming please.

can you redo your links, its taking me to the newegg homepage for some reason?

They should be fixed now, sorry about that.

 

[theDoItYourselfAmeture]

I'd go for the R9 280x, its newer, draws less power and runs better on battlefield 4.

http://www.newegg.com/Product/Product.aspx?Item=N82E16814127759
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125475
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121803

 

[CheapMerc]

All about budget in my opinion. I got 6950 crossfire because I'm a houso marriedy. 280x will perform better, but if you are skint. If you are asking what to get means you can get 280x so get 280x.