Question Green dots on hdmi

[j0hud]

recently i just upgrade to new 144hz monitor. The connection is good on vga but cant handle 144hz only 60hz is the max so i tried using hdmi cable to achieve 120hz but when i did that the screen suddenly appeared green dots everywhere and the display is just horrible sometimes it off sometimes on by itself. I really hope there will be explanation to this problem

 

[j0hud]

recently i just upgrade to new 144hz monitor. The connection is good on vga but cant handle 144hz only 60hz is the max so i tried using hdmi cable to achieve 120hz but when i did that the screen suddenly appeared green dots everywhere and the display is just horrible sometimes it off sometimes on by itself. I really hope there will be explanation to this problem

View: https://www.youtube.com/watch?v=TX_cgzYY2iA&feature=emb_title
this is for reference