I also have similar problem with AMD FX8800P carrizo.
My Laptop is Acer E5-452G-F3WH running on W10 64bit
I upgrade memory to 16GB@1600mhz dual channel.
For games like DOTA2, my CPU is running fine at 2.1Ghz or more with around 60% CPU usage.
But integrated GPU R7 is running at 400Mhz (95% plus GPU usage), but never reach its default clock (720Mhz).
Framerate is 25-40 @ 1366X768 on "best looking graphic setting"
My laptop also has R5 335m, but It just won't work with DOTA2.
Switchable graphic setting is set as "high performance" but it always use my integrated GPU
I have tried all drivers and google for all information.
You may require a new BIOS that allows you to disable the integrated GPU. Try contacting Acer. Laptop makers rarely allow users to make many adjustments to their laptops however.