Black Screen Error

I installed using opencore 0.5.8 but I am getting black screen while watching videos or even opening screen saver and also when opening games. Please help

I have attached a video https://youtu.be/Av8zVkMESL4

Specs:

I5 7500

Asus B250F gaming board

8gb ddr4 corsair

120gb ssd

GT730 2gb ddr5 graphics..

https://reddit.com/link/gwb0qa/video/g8rda7t63u251/player