Can't get video signal?

[asalow12]

I'm trying to put one of my old computers back together and i'm having problems. I can't get a video signal. I've tried two different mobo's, one works for sure, and two different pci xpress cards, and two processors, but it works fine with the old hp machine i'm using right now. Is there something that i'm overlooking hooking up that is making it not work?

 

[adweston]

Try replacing the power supply. If a power supply can't stabilize the voltages, especially the 3.3V, it won't send the power good signal. If that happens, the fans will spin. the drives will power up, but the computer won't post. In other words, it will look like the computer is working when in fact it isn't.