Originally Posted by RB Snake
The factory overclocked cards clock speed does not have to match your reference card speed, with Kepler they can run independently. My 2x 680s both boost to different speeds, card 1 sits at 1176Mhz and the other sits at about 1200Mhz. They don't need to synchronize.
but the fact they are crashing instantly on load is indicating a problem
the base core speed should still match, the bios versions are different this might cause a different boost clock
there are rare instances where when there are different bios version between cards it can cause conflict see in your screenie the bios is different.
I have to be honest I am out of ideas apart from driver cleaner to remove NVidia drivers and re install NVidia drivers then AB