So this fall I am upgrading to a 780 but I don't want to get rid of my 660ti, i want to use it as an extra for really heavy load games, I am wondering if this is possible or if the game will only use the 780 or the 660ti and not both. i know this is an odd question but please be nice._.
You can make the 660 a dedicated physx card. It would compliment the 780 nicely I think.
SLI only works for identical GPU models. Even if the two GPU's are based on the same chip, but different models (ie the GTX 680 and 670, both based on GK104), it won't work. You can use the 660-Ti as a dedicated PhysX card, but not too many games utilize PhysX. You can also do some Folding@Home.
im not much of a bitcoin person but could I use the 660ti for mining and use the 780 just for gaming, another thing wouldnt this cause a cpu bottleneck with that much power, and how would I dedicate it to physx? and or in game physics and such?
dedicating it to physx is merely a checkbox in the nvidia control panel.