It is indeed the CPU ! it was spiking over gpu few times and that's when the frame drop happened
** Any image wider than 1280 pixels should be linked or placed in spoiler tags **
Sorry for the bad image for some reason printscr screenshot and afterburner screenshots where not working....
And also the gpu is about centimeter above cpu on the graph when normal fps, I will test it on normal server to see.
Any suggestions ?
What resolution are you running? Because in that screenshot you're running 720P and what appears to be resolution scaling taking the resolution up to 1536x864. You should be running 1080P or similar in full screen mode, not Borderless or Windowed mode.
Mantle will only run in 64 bit mode.