XPS 710 No signal issue

I start up my computer. Everything is green, fans roaring then cool down, I get the 2 - 4 lights, and then the monitor says...No signal. I have changed the monitor, the cord linking the computer to the monitor, I have bought a new graphics hardware and installed that.....still No Signal. I walk away frustrated - cool myself down. The next day I try it again and it starts up just fine. It's a miracle. I turn it off. Come back the next day and :( the computer is giving me no signal again and the 2-4 green lights are there again.

So I get sparodic performance. Any ideas?