Question expensive graphic card no function

[CarriedNeedsHelp]

I bought NVIDIA GeForce RTX 2080 two days ago and everything is installed perfectly all drivers are up to date and all that, when i load into Overwatch with medium settings i cand max 20 fps and lowest been 5 fps,I have plenty of fans but still it heats up to 80-85C when i play, after maybe 20 minute of trying out games my screen will be turned off, sort off. I can still hear music etc but my screen is black and I will get a message saying it cannot find or be connected to the hdmi or Dp port which i tried to switch both caples and all, HELP

 

[drivinfast247]

Please list all PC specs including PSU make and model.