Oh, and in case anyone finds this kind of stuff interesting - Here is an article discussing the new Nvidia 750 TI and it's hash rate. If you notice, it only uses 60W's @ full load versus the 300W a 290. Yes it is a lower hash rate, but imagine having 6 of these on 1 500W psu. The savings in electricity alone would be nice! Fitting 6 on 1 motherboard to make up for the hash rate difference may not be so nice!

http://www.pcper.com/news/General-Tech/NVIDIA-Coin-Mining-Performance-Increases-Maxwell-and-GTX-750-Ti