No video signal on multiple boards.

[NastyNoah]

This all started with a BB1, that had a bad power supply.  I swapped out the power supply, and booted up with clear card.  Everything was working.  Put in the game and OS and it locked up while loading   I left it going to see if it might recover.  After 10-15 min the screen went black, and then I would only get a "No Signal" on the monitor. All light and fans are coming on.   I thought maybe the graphics card overheated, so I put in a known working BB1 board I pulled from another machine.  Still "No signal", had a friend bring over 2 of his BB1s, No signal.  Put the working board back in the original machine, and now it is doing the same thing "No Signal".  Out of 4 boards and 2 machines, I get no signal on all of them.   All back plane lights are on, MPU lights are on, fans are running, re-seated the ram, made sure mpu was pushed down all the way, tested monitors with PC and they were fine.   What could it be that is causing there to be no signal on everything???    I am stumped!!!!!!   

[NastyNoah]

I dove into this again tonight with some BB2 boards, and still having the No signal issue.  Monitor works perfect when hooked to a PC.  All lights and fans are going, on each of the boards on both machines.  What could it be?    I'm willing to try anything at this point.