To everyone who still has this problem, I found a solution!
Re-installing windows did not really help because windows was automatically installing GPU drivers including nvidia 3d vision which was not supported by my monitor (i guess this was the problem).
What i did after was again a clean install of windows without internet connection.
I installed the newest drivers which i preloaded before manually: GPU, Chipset, Network drivers etc without internet connection.
When the installation was complete I connected to the internet and did a quick windows update.
Afterthat I overclocked my display to 165Hz and everything is working smooth again.