Gtx 670 or 7970?

Need help on which GPU to get. Will be used with a 8350 cpu Asus sabretooth 990fx r.2

7970 will no doubt be faster, so unless you need CUDA get the 7970

How big is the difference between the 670 and 7970?

"In theory, the Radeon HD 7970 should be 38% faster than the Geforce GTX 670 in general, due to its higher data rate."

 - Hardwarecompare.com 

Unless you need CUDA as stated above

Yeah, unless you need CUDA, the 7970 will be much faster, especially if you overclock it. Current drivers make it a solid contender for the GTX 680.

7970 beats the 680 in most games and is very close in the games it doesn't beat it in.