Not much to work with my bet is the shop would be the next stop as given this much detail it looks like any guess would be just that.
If this was mine I may know all about the machine but here all I can suggest is to replace the video card.
I've baffled with this problem, and am desperate for suggestions. Unfortunately, I haven't found the right words to feed Google, so I'm trying here.
I've got a PC I built a few months ago. It was economical (aka cheap ) but this is just a basic email/etc. machine. I'm using the on-board VGA.
Here the thing. A couple days ago, the monitor just stopped working. I've plugged 2 other computers into this monitor and everything is fine. I've connected the PC to 2 other monitors, and everything is fine. Problem is when this CERTAIN computer is connected to this CERTAIN monitor. I get no video--can't even see the POST message, although it appears to be booting.
Monitor status light goes from amber (no signal) to a flashing green, so it's detecting something, but not happy with it.
Does this sound more like a bad video signal, and I can fix it with a video card? Or maybe a monitor that is getting more particular on it's signal as it dies? Open to suggestions!