Increase pagefile to 56 GB (7 x 8gb). Which driver are you using? Also, recheck all your risers, PSU connectors, if everything is connected ok.
The latest nVidia drivers. What's the general consensus on the most stable drivers?
Have you increased the pagefile? I haven't tried the latest drivers yet, usually I wait for a while. Currently I'm running 390.65 and I don't have any problems.