Well, it's the Crimson drivers. These drops are happening to me too and many others in a lot of games. I have same drops in BF4, amongst other games, which Catalyst driver didn't have. I've tried at least 20 different things but it looks like there's no fix.
Just install Catalyst 15.11.1 again if you wanna enjoy your 390 without these crappy drops and maybe just MAYBE they'll fix this mess in the next Crimson.
Yep same low gpu usage in some games, and even in AMD's demo.
This is embracing.
If you still have this problem i suggest you use ClockBlocker. It was made to fix this issue and most ppl with these performance problems use it. I use it and it works great.
HII TO ALL WHO ARE HAVING THIS TWO PROBLEMS
I HAVE GOT THE SOLUTIONS FOR BOTH OF IT
As you might have noticed lot of people with the R9 390 are complaining to this problems
The first and easy one is with the MSI Afterburner
It shows that the gpu load is down and up or we call it the card has spikes going form 100% to down 0% and so on
This problem is solved by going to the MSI Afterburner settings
and check the box for ENABLE UNIFIED GPU USAGE MONITORING
NOW YOU WILL SEE THE REAL GPU LOAD
THE NEXT THING WHAT CAN HAPPEN TO YOU OR DONT HAVE TO BE
IS THAT YOU WILL NOW SEE THAT YOU HAVE GPU LOAD AT LIKE 55%
DEPANDING ON THE GAME YOU ARE MAYBE A BIT MORE A BIT LESS
THIS IS NOT A CPU BOTTLENECK
I HAVE THE i3 4130 and the R9 390 GIGABYTE AND HAD THIS PROBLEM
THAT ALL BENCHMARKS ARE GIVING ME 100% IF GPU LOAD
AND THE BENCHMARKS ARE GIVING ME THE RESULT AS IT SHOULD BE FOR
THE R9 390 IN HEAVEN OR VALLEY
BUT GAMES ARE JUST LIKE 50% GPU LOAD
THIS IS NOT AN DRIVER ISSUE OR A BAD GPU OR LIKE I SAID A BOTTLENECK BY THE CPU
YOU JUST GO TO THE SETTINGS OF THE NEW CRIMSON DRIVER
OR EVAN AN OLD CATALYST CONTROL CENTER
AND FIND THE SETTING OF ANTI ALIASING METHOD AND SET IT TO ADAPTIVE
THATS IT...NOW YOU WILL SEE YOUR GPU WILL BE FULLY USED..
IF YOU SET THE METHOD TO SUPERSAMPLING THE GPU WILL ALWAYS BE USED TO 100%
BUT YOU WILL LOSE ON THE FPS..
BUT IF YOU JUST SET IT TO ADAPTIVE...YOU WILL GET THE GPU LIKE IN BETWEEN 80 AND UP TO 100% USED
BUT WILL NOT BE LOOSING ON THE FRAMES
AND OF COURSE THE SETTINGS IN THE GAME YOU PLAY ITSELF DEPENDS IF IT NOW WILL BE LIKE ALL TIME 100%
OR IF YOU WILL GET MORE FPS BUT HAVE IT GOING FROM 80% TO 100%
IT WILL WORK
NO BAD GPU
JUST SOME GPU SETTINGS
GOOD GAMING AND GOOD LUCK