Thanks for replying guys, the FPS is down when my camera is directed towards some area. One example is when i'm facing adventurer guild in quicksand, my fps down to 40ish, and when i faced backwards again, it back to 120, of course it seems its not only in adventurer guild because i have experienced fps down in many area. Coincidentally i just bought a new modem and router, and i'm using LAN connection. And my GPU temp is 60 - 70 ish when playing. There was one time when its gone up to 80 too haha.

But i think i'm now getting used to it, have tried so many things but couldn't fixed it, thank you for the help guys!