This has been bugging me and tons of other people for a long time now and i'd like to get a definitive answer on the subject.

FX-8350 4.3ghz

R9-270 xfire with HD7870 (yes they are compatable)

12 gigs of ram

So anyway my GPU usage never exceeds 50% on both GPU's (monitored in afterburner)

CPU usage seems active on all cores and doesn't exceed 70%

I've done a sweep of all my old drivers. I've tried crimson 16.1.1 but that didn't help so i did another sweep and i'm back on 15.12 drivers.

I've tried running crossfire in crysis 3 amd mode.

Tried converting to the old patch (for amd, i forget what version but there's a write up somewhere about it)

I don't see any bottleneck. Considering how many people are having the same issue, even on a single card i think the game is broken.

Are we just screwed?

EDIT: I'm going through this guide now and i'll report back http://www.gamesas.com/topic/1588492-guide-for-improving-fallout-4-performance-on-amd/

You may have to lower your max shadow distance for the shadow boost, my settings are optimal on an I7 4770k and an AMD R9 fury X a good starting point. I wish I could say I got 70% cpu usage I never see anything more than 40-50%=/ There will be a few things you may have to turn down with your setup and maybe you're resolution.

Yeah trying everything on that linked post didn't help one bit. I've turned shadows off completely on fallout4configtool and still managed the exact same 40ish FPS in diamond city with GPU's sitting at 20 and 40 percent. I'm just confused why people are suggesting to change graphics settings for low GPU usage. My goal is to have the game run and use the full potential of my GPU's, not to turn things down to run better. Turning things down doesn't help anyway, just lowers GPU usage even more.

If you used RadeonPro you should see an improvement that is at least the case for the R9 380/380x, 390/390X, and all the new HBM cards.