Fallout 4 seems to run fine even on budget PCs.
~40 average fps + ~30 minimum fps with i3 + GTX750 ti in settings similar to the console versions: http://www.eurogamer.net/articles/digitalfoundry-2015-fallout-4-performance-analysis
~40 average fps + ~30 minimum fps with GTX760 or R9 270X in 1920x1080 in maxed settings: http://www.pcgameshardware.de/Fallout-4-Spiel-18293/Specials/Test-Benchmark-vor-Release-1177284/