i try to keep it simple. it more then one part when it comes to video and computers booting or (posting).
on the pc with no video do you see the case and cpu fans spin up and is there any beeps from it?? for a pc to work you need power and a working motherboard. if this is your first build check that both the 24 pin atx and the 8/4 pin eps power plugs are connected. if there are check that you did not short the mb to the case. with video cards some of them need extra power check the video card to see if there any 6 or 8 pin connectors on it. if there are there make sure you connect power to them.
when you hit the on switch on your pc case it turns on a small electronic switch on the mb. the power supply will turn on and output three main rails. (3.3 5.0 and 12v.) with power the mb will start to post. the low level post is a bios post. the bios chip set up the mb and hands off to the cpu. in the bios post the bios check that the ram and video are working. if not you get a cmos beep code or an error on screen. when a pc is running it the gpu and gpu firmware that runs the video cards. the video drivers just tell the os what the video card can do and it hardware info. the video data is sent back and forth on the pci bus.
the short beep is a cmos beep. if it doing that then the video card..video card cable or the monitor went bad. if the monitor works on another pc check that the video cable has no bent pins. if the cable is fine see if someone has a older video card you can use for testing.
I took everything out of that case, (well I did before but it did nothing.)
And I saw this thread something to do with a breadboard.
Anyway so I set up the board there and I configured everything on it, set up the power, cpu and 1 stick of ram, as well as the hard drive and it posted just fine.
So I shut it down and added piece by piece again post came back fine.
Their was one problem but it occured outside of the case.
Picture all your components sitting there on a desk, all hooked up cables and all, and then the damn dog pulls the motherboard and everything else right down slamming into the floor.
So thats how the little plastic L click in the sata drive broke off. Sure it's old as hell, but hey that heavy sucker goes and goes quiet.
Anyway the pins wern't damaged so I just stuck that cable in there, rested it up against itself, then twist tied it to the power cable beside it, then twist tied it again to the nook in the dvd drive bay to keep to up. Worked fine cause i'm sittn here with it running full steam.
As for what was wrong, ive no idea. Maybe a short in the case but doesn't seem likely with it mounted. So theirs ur answer. When ur pc's flippn ya the bird, get the bread board and build on it.