My monitor turns on and displays the "No signal" box so long as the monitor is not connected to a computer. But if I attach either the VGA or DVI cables, the monitor shuts down. And it won't turn on with a cable attached. The fact that I see the "No Signal" box, without a cable attached, leads me to believe that the problem is with the video processor (main board) raher than the PSU board. I've tried disconnecting the backlight cables on the PSU board and the video cables from the processor board. Still shuts down when I attach the computer cable. IOW, the power led goes out.