Okay let me start off by saying I am extremely frustrated - fallout 4 is lagging so bad it's hardy playable and I have double checked all drivers on my PC are up to date. My specs are CPU I7 4790 3.6GHz, Geforce GTX 980 Ti, 16 GB RAM running 64bit windows 7. I should also mention this lagging issue is on the lowest setting which as you can see my rig should be able to run higher than minimum quality. Any ideas because frankly I'm out after trying all day to get it working right.

should also mention while trying to fix this I shut down all non essential programs excespt steam (which is how I ordered it) an task manager. Task manager shows a max of 14% CPU usage and max43% memory usage so this is why I am really confused and frankly pissed off at the moment.

Okay nevermind it was an issue with the GPU - apparently you can run off the CPU when plugged into the GPU but unplugging it then replugging it and getting it to check for updates fixed it

I'm having similar problems, you say you unplugged the gpu from the motherboard?