Need help with my new pc [urgent]

I bought a whole new pc today, and i just finished building it.
When i press my powerbutton, everything starts (cpu-fan, dvd-rw, light’s go on)
but i my screen shows nothing. My HD3870 is connected properly (fan spinning), but why don’t i get anything??
ty for ur help
Answer #1
It is a plug&play monitor?
Answer #2
yup, it works with this pc without any softwareinterferance
Answer #3
i just unplugged my extra powercabel to the videocard and my fan started to go faster!!!
any idea’s?
Answer #4
This happend to me when i had a 9550 256mb. My problem was that the card was faulty so i took it back and got a new 1. try plug it into all the monitor plugs avaliable. try to swap the graphics cards around? i dont know much im just trying anything i can think of lol
Answer #5
i found the problem, the card itself is broken :s
i used my 6600GT and my new pc was shining like a star… taking it back tomorrow to get a new one
Answer #6
You sure that your powersupply can power the videocard?
Answer #7
it’s a 650W Tagan pov powersupply, it normaly can handle 2 of them at the same time, so there’s no problem