Macbook Pro external display bootcamp problem

[dannyterrazza]

I have a Macbook Pro mid 2012 15" and I have a problem on bootcamp using external display. I am doing SMC reset everytime before starting Windows. I have also throttlestop and nvidiainspector installed for preventing cpu/gpu throttling. My problem is games run fine on macbook display but when I connect displayport adapter to my monitor and choose external monitor as the main display, games start to lag in random intervals. I tried clamshell with and without clamshell mode. I can only play without lag when I disconnect the moitor cabla and play it on its own display. Can you suggest a solution? Thanks