If you find your self a little confused on how and where to locate the places in registry.
Read the very first post of this thread. It should help clear up some questions you may have.
The reasion I posted to the above link is because after nvidia M40 some things stopped working and new ways of some parts has changed with the P100 and P40 cards to make them the main card used for video and change the mode to WDDM.