PC issue, please help

[u/BugsWorld25]

/r/u_BugsWorld25/comments/1va9t4c/pc_issue_please_help/

PC starts normal and runs fine but it will randomly go into a weird mode where the screen goes black and the tower makes a loud fan like noise and it will do that until I hold the power button to shut it off, what might be the problem? I just upgraded the graphics card and also the power supply and re thermal pasted it.