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AMD right now are the winner on performance for a given price - however it's worth mentioning that nVidia are meant to be doing some price cuts soon, probably as a response to the r9 290x. There was a thread around somewhere. With no details about what is getting cheaper and by how much I'd pick an AMD card for sure just now, but if you're not in a hurry you could wait and find out...So reckoning the AMD route is the way forward?
Would you not got for HIS 7970 or the Asus 7970 Matrix
I wouldn't, because I'd be paying a fair bit more for an average of only around an extra 5% performance gain.
It's more than 5%. The 7970 is a good 20-30% faster.