Monitor/Video Card

I am helping a friend with his computer and have run into the following problems. Firstly, he was not able to get the computer to turn on so I disconnected the power supply and connected a different one to it. The computer turned on, which was good, but the monitor would not come out of sleep mode. I disconnected the new power supply and reattached the old one and it worked as well...seems he had somehow accidentally hit the power switch on the unit itself. So, there is power going to the computer, drives open and close etc., but the monitor will not come out of sleep mode. When I disconnect the monitor the screen shows the colorful "No Signal" sign, but once I connect it again it immediately goes into sleep mode.

I am not sure if this is a video/graphics card problem or possibly malware of some sort. I looked over the video/graphics card and nothing appears to be amiss, but I am not an expert on such things. I would think that since it recognizes when it is plugged in it should at least come out of sleep mode. Here again I am no expert. I appreciate any and all ideas you may have to help me out. I am reasonably certain it is not the monitor since it shows the no signal sign when unplugged.

Thank you yet again you bunch of freakin' geeks.

 

Something kinda obvious, but an easy mistake to make :
if there is a video card installed, make sure that you are connecting the monitor to the card, and not the motherboard.

 

Unfortunately I do not have another PC to test the monitor on, but I would gather it is working fine if I am getting the No Signal sign when I disconnect it from the computer. Another cable is something I can try, will post results. I reseated it a few times. I will try the weird suggestion, stranger things have happened and worked..lol. I am definitely plugging it into the card. Will report back after trying the above. Thanks.