Question black screen Crashing no display

Oct 9, 2020
Before i return it to bestbuy i Just got a cyberpower pc with the rtx 3080 i9-10850k about 1 hour of using it browsing the internet the screen goes black and i have no display restarting it doesnt work still no display so i rip the plug out of the wall waited and plugged it back in and it worked straight away i tried bench marking AC odyssey half way through screen goes all colorful and 3 big stripes on the screen and its frozen hard shutdown fixed it then 20 mins later watching youtube screen goes black crashes and no display again, this time i cannot fix it on bootup..pc runs just no screen no nothing. Thinking it was the GPU i took it out put it in my other pc and it works fine so its not the Graphics card. What else could it be? trying not to return it since the 3080's are a nightmare to get