Just for reference
 
My GTX 750ti SC EVGA cards do 1.79 Mhash average (50 of these on spr at the moment) with no OC beyond factory.  These are purpose built rigs with 8gb of RAM and Celeron CPUs
 
3 x GTX 950 does right at 2 Mhash alongside 2 750ti in the same machine.

A GTX 970 windforce does 4.5Mhash, but this is a much faster CPU (don't know if this matters).

I have 2 5-card GTX 960 machines that are absolute MONSTERS at everything I have tried them on.  I don't remember the exact hashrate they did on spr, but I think they were about 500 watts at the wall.  They are on something else at the moment, and at a different location, so I can't verify.

I haven't measured the power draw any of my faster cards, because they are not dedicated miners.  I'll try to get the 970 numbers for reference
 
This is using sp mod 8 private miner, because he hasn't sent me any updates.  My email address changed after I bought it, so I can't blame him.  But I have been EXTREMELY happy with everything I have purchased from him.

ALL are rock solid, and will run for a month+ at a time.  A 6-card 750ti machine will draw 375 watts at the wall with no voltage mods.  That could probably be significantly lower, but I haven't played with it because they are dead stable on anything I have mined with them