https://forum.litecoin.net/index.php/topic,2870.0.htmlI put this together to compare different cards. It's taken from the Github user reported stats. Personally from what I've read and calculated the only 2 cards to even consider are the 7850 and 7950, no way the 7970. It has a decent KHash/s to cost ratio but one of the worst KHash/s to watt ratios. Also as has been mentioned in this thread, the 7970's seem to have more issues as compared to the 7950's which plug and play better. I would go for the 7950's instead of the 7850's simply because they have the better efficiency ratios per dollar and watt. The only exception is the 7850's KHash/s per watt in 5-7 card setups but considering most people don't seem to go above 4 card setups and we're talking between .02-.08 watts per KHash/s difference. When you factor in the fact that with 7950's you get more total hashing power from one physical setup ie more density it is a no-brainer. Just my 2 cents.