Power Save Mode Problem

[savvybubb]

So, I recently got a Gaming PC from a yard sale(don’t hate) and I got it for free. It was free because it didn’t power on because the power button cable wasn’t plugged in. Anyway, when I turn on the PC and plug it into the monitor, it says “Digital Input, In Power Save Mode, Press any key on the keyboard or mouse.” Well I tried that and nothing happens. What do I do to fix this?

 

[CountMike]

That's message from monitor OSD, looks like GPU is not sending any signal to it.