Question : Problem: No Signal from Monitor

Have a 22" Acer LCD hooked up to an eMachines PC, Windows XP.  The other night, computer was working fine.  next morning, we are receiving "no signal" error from monitor.  Monitor is brand new, computer is somewhat older (5-7 years maybe).
I have swapped cables, same problem.  moved monitor to another pc, it works fine.  went ahead and swapped out video cards, still receiving same problem.  This pc is not networked, so i can't think of a way to try to connect to see if it's even booting up.  the pc turns on and fan blows, hd makes noise, etc, but the monitor turns on and displays "acer" logo for about 5 seconds, then says "no signal" then shuts down into into power saver mode.  any monitor display issues i've had in the past were always a faulty monitor, faulty cable, or bad video card.  i've eliminated all 3 of these, leaving only the mobo (or whatever sends the signal to video cards).  i can't test the original onboard video because i'm assuming it was disabled when the add-on video card was installed, and i can't see anything to enable it.. i guess my real question is if there are any other diagnositc/troubleshooting steps i can take before assuming the problem is somewhere within the pc (beyond the video card).  As it is an older pc, if the mobo or something major is shot, we will probably just replace the computer.  however, this is my parents pc, and i want to make sure that is the problem before purchasing a new one.  any help would be appreciated!  

Answer : Problem: No Signal from Monitor

have you tried another monitor on this pc? how about hitting f10 or f12 when booting up and see if you can get into the BIOS.  or F8 for safe mode. both of those will give a video signal that most monitors can display.  If someone somehow set the video card to output a signal that the monitor can't display it may exhibit the same symptoms you are seeing.