So, first off,win10 probs, upgrade/ISO install ?
A site well worth a visit tenforums.com/
Keep in mind. the 480 is not a high end card (older 390x is better imo),FO4 is pretty h.a.r.d on amd cards(nv godrays).
If you carried over any old win7/8 software, un-install/delete it.
Try a Clean Install AMD Graphics Drivers download/install full driver pack(not min.setup)
Also, any 3rd party oc/optimizing software may cause conflict with wattman (un-install/delete, turn off hw.acc in browsers(unless needed ?).
For troubleshooting, all startup apps/.programs should be disabled in task manager.
For good gaming, read the related games' graphics tweak guides (easily found on websearch).
If you want to go nv, your choice, but threats of that usually deter many of us offering possible remedies.
I deleted my FO4 graphics guide long ago(1200+hrs @constant 50+-60 fps on a 7970), so you need to do a bit of learning before blaming hardware..