Sounds more like the monitor. If your graphics card is disconnected or u/s, you usually get a message on your screen to the effect "check your video input" or something like.
Do you get any "white lettering on black background" on the monitor during initial stage of boot?
Forget px unit if fans/drives are still working.
Check all connection to your monitor and don't connect/disconnect mains WITHOUT powering down Windows (press and hold the PC ON button until everything stops).