I know I'm late to the party as far as responses go, but I had been running into the same issues recently when I started FO4 back up, granted my hardware is older, (R2700 & 1070ti with 32GB RAM), but the low system utilization is the same as you, with the GPU never more than 40% utilization, with the CPU around the same. (Usually hovers around 25-30%) I used HWinfo and found that I wasn't utilizing CPU cores efficiently. I read other people's "fixes" to .ini files to tell the game to use more threads, but it didn't seem to do anything. What has is... This mod has helped in the condensed areas, https://www.nexusmods.com/fallout4/mods/46403 I did OC my CPU to help with data transfer to the GPU, I also went into Task Manager, in the "Details" tab and selected Fallout4.exe, right click, and set priority to high. Then selected "Set Affinity", which shows options for which CPU threads to use. Having priority set to high, you need to uncheck at least the first two threads for system resources, then you can leave the rest checked. Having 16 CPU threads, I used Ryzen Master to show me which Cores are my quickest, then set the CPU threads accordingly. I have the game set to utilize 5 cores out of the eight, (My #eight button is broken lol). The game still has it's moments, but the FPS drops and stutters are less apparent, and miles better than it was before. One thing to note, Task Manager does not save the CPU threads you checked/unchecked, so this is something that you have to do every time you boot up the game. I also uncapped the FPS in the falloutprefs.ini, then went into Nvidia control panel, and went to "manage 3d settings", then selected "program settings" to add FO4 to the list. Then set the Max Frame Rate to 60FPS, power management "prefer Max performance", and Vertical Sync to "Adaptive", which I'm still messing around with.
