Not exactly freezes, it just turns off... as in monitor goes dark black and the LED that is either orange/blue depending if the monitor is on goes orange as if the computer is turned off.
But I still hear stuff(music, streams, skype calls) going on in the background except for fallout which probably crashed along with the monitor...
Also this started happening ever since I updated drivers to latest ones today in the morning before playing fallout, it made the performance better but keeps crashing every 5 to 10 minutes and like I said sometimes also crashes my monitor.
I tried uninstalling the new drivers and installing an older one [NVIDIA 355.60] but it didn't fix it.