I previously had an older AMD card, but upgraded to an NVIDIA GTX 970. What I noticed, with any set of drivers, is that after playing MH for a little while the graphics would just sort of lock up. Nothing would get me out of it and I'd have to reboot. And this was happening a LOT. This didn't happen with other games like The Division, etc. Only seemed to affect MH.
I did some searching and found a suggestion. Use the MSI Afterburner program to UNDER clock the graphics card. This is exactly what I did. I downloaded this free program and underclocked it by setting power limit to 90% and setting core clock in MHz to -100. With these settings, I never get the lock ups. I know it's working, too, because I occasionally forget to turn on the MSI Afterburner before playing MH and I get the crash within 45 min to an hour.
I am not really a hardware/graphics expert (more of an enterprise level computer expert) so there may be other/better advice out there. Mostly I am regretting getting the NVIDIA, but not going to throw more money on another card for a while because this seems to be the only thing affected. Just some take it or leave it advice if you have the same trouble as me and happen to see this.