That on google finds the usual method. Remove, unplug what you can until it comes back up.
If the PC has onboard video, you can pop the GPU out and see if that's it. Be sure to use The Dead PC search on google. You find it's the usual method of reduce until it beeps in protest.
I recently built a pc, it was working fine until it crashed and now it turns on (fans spin, leds, etc) but there is no signal going to the monitor. The fan on the gpu spins for about 30s and then turns off, showing it has power. I am assuming its a dead gpu but that would seem kinda weird. Any help would be great thanks.