So perhaps this is a bit off topic, but you guys seem like a knowledge group. Are the 750 ti's the most power efficient of the of the Maxwell cards? Thanks.
YES--
The 750ti cards are still the best power-wise. The 970 cards produce a good ratio of hash per card, so setup expense is lower. as fewer cards + motherboards and hardware are required for any specific hash rate. A 750ti rig can be built inexpensively, too, if you shop carefully. It will use the least elecricity per card, generally.
Hardware review websites and forums will draw up detailed comparison charts, check the google results.
I am hoping that a 950ti will be released that changes the game; a card faster than a 750ti and that uses less or the same power. --scryptr